IT News

A mix of industry and technical, traditional and next generation, dev and ops

Linux News and Articles

Linux-centric news and articles

Linux Message Boards and Forums

Resources for troubleshooting and technical questions

Mailing Lists - No link, there's like 4 trillion of them
IRC - Same as above
Arch Linux BBS - Official
Ask Fedora - Official
Ask Ubuntu - StackExchange
CentOS Forums - Official
Fedora Forums
JustLinux Forums
LinuxForums.org
LinuxQuestions.org
linux.stackexchange.com - StackExchange
Linux Mint Forums - Official
Red Hat Support Portal - Subscription required
serverfault.com - StackExchange
superuser.com - StackExchange
SUSE / SLES Support Portal and Knowledge Base - Official
SUSE Forums - Official
UbuntuForums.org - Official
Unix.com Forums

Asset Management

Asset management, inventories, asset discovery, CMDB, and IPAM - see also Configuration Management

Collins - Infrastructure source of truth, created by Tumblr -- Scala
iTop - IT Service Management (ITSM), asset tracking, and ITIL -- PHP
Fusion Inventory - Multi-lingual, can be paired with GLPI for a killer solution -- perl
Genesis - Hardware discovery, by Tumblr, can report to Collins -- Ruby
GestioIP - IP address management (IPAM), web based, supports discovery -- perl
GLPI - Also provides license management, software auditing, and ticketing -- PHP
IP Plan - IPAM -- PHP
ITDB (IT ITems DataBase) - Includes purchase order management, floor plans, and ISO20000-like features -- PHP
NetBox - IPAM and DCIM by Digital Ocean -- Python
Netdisco - Web-based network management and discovery tool, written in perl, uses SNMP -- perl
NIPAP - Next-generation IPAM -- Python
OCS-NG (OCS Inventory NG) - Automated inventory, deployment system, can sync with GLPI -- perl
openDCIM - Data center infrastructure management -- PHP
Open-AudIT - Track and report assets and configurations, supports Windows too -- PHP
phpIPAM - IPAM -- PHP
RackTables - Data center asset management, being updated again! -- PHP
racktables-contribs - RackTables user-contributed plugins -- PHP
Ralph - DCIM and CMDB, supports auto-discovery -- Python pip
Snipe-IT - Uses Bootstrap, web based, supports mobile -- PHP

AWS Tools

Tools for interacting with the Amazon Web Services ecosystem

Aminator - Create application-specific custom AMIs, by Netflix -- Python
asecurecloud - Create a stack and have it output as CF or AWS CLI pre-secured using best practices -- in-browser
assume-role - CLI tool making it easy to assume IAM roles through an AWS Bastion account -- shell
awacs (Amazon Web Access Control Subsystem) - Allows for easier creation of AWS Access Policy Language JSON by writing Python code to describe the AWS policies -- Python pip
Awesome AWS - Curated list of AWS resources -- collection
awless - Another AWS CLI, give it a try -- Golang
aws-shell (formerly Supercharged AWS CLI (SAWS)) - The best CLI for interacting with AWS -- Python pip
aws-vault - A vault for securely storing and accessing AWS credentials in development environments -- Golang
AWSConsoleRecorder - Records actions made in the AWS Management Console and outputs the equivalent CLI/SDK commands and CloudFormation/Terraform templates -- Chrome `JavaScript
AWS Amplify - Front end JS suite that provides a templated foundation for cloud-centric apps including authn, analytics, API, push notifications, Graph QL, and more -- JavaScript
AWS Breaking Changes - List of changes announced for AWS that may break existing code -- collection
AWS Extend Switch Roles - Extend your AWS IAM switching roles by Chrome extension or Firefox add-on -- JavaScript
AWS SAM Local - CLI tool for local development and testing of Lambda applications -- Golang
azcopy - Official CLI for copying data to/from Microsoft Azure Blob, File, and Table storage -- closed source
boto3 - The AWS SDK for Python 3 -- Python
boto3_type_annotations - Adds code completion in IDEs such as PyCharm -- Python
botostubs - boto3 code assistance for any API in any IDE, always up to date -- Python
Chalice - Microframework for writing and testing serverless apps in Python -- Python
Chamber - Parameter Store + IAM for secrets including at rest protection, audit trail, and access control policies, by Segment -- Golang
Chrome AWS SAML Token Expiry Reminder (CASTER) - Automatically re-logs into AWS via ADFS before credentials expire -- Chrome
CloudBerry Explorer - Windows client for accessing AWS S3 buckets -- closed source Windows
CloudCraft - Create professional AWS architecture diagrams -- in-browser
CloudFormation Checklist - A list of all elements you need to have / to test before launching your infra to production -- collection
CloudFormation Roadmap - Official roadmap -- article
CloudMapper - Generates network diagrams of Amazon Web Services (AWS) environments and displays them via your browser, by Duo Security -- Python
CloudSploit Scans - Scan AWS accounts for security risks -- JavaScript
credstash - Secrets management using AWS KMS -- Python pip
eb_deploy - Elastic Beanstalk blue-green deployment automation -- Ruby gem
ec2-price-check - Gives a quick price check for an instance type -- shell
ec2instances.info - Open source and up to date instance price comparison tool -- Python
eksctl - CLI tool for creating and managing clusters on AWS EKS -- Golang
Empire - PaaS built on top of Amazon EC2 Container Service (ECS) -- Golang
Fargate - CLI for AWS Fargate, unofficial -- Golang
Force MFA - Allows users to manage their own passwords and MFA devices but nothing else unless they authenticate with MFA, also makes API calls require MFA -- policy
Former2 - Generate CloudFormation / Terraform / Troposphere templates from your existing AWS resources via self-hosted web GUI -- JavaScript
haproxy-autoscale - Wrapper for haproxy that handles auto-scaling EC2 instances -- Python
Ice - AWS usage tool, by Netflix -- Grails
jungle - awscli wrapper to make commands simpler and more UNIX-like -- Python pip
kappa - CLI tool that makes it easier to deploy, update, and test Lambda functions -- Python
localstack - A fully functional local AWS cloud stack for offline dev and test -- Python
Moto - Library that allows your Python tests to easily mock out the boto library -- Python pip
My Arsenal of AWS Security Tools - List of open source tools for AWS security: defensive, offensive, auditing, DFIR, etc -- collection
Prowler - For AWS account security assessment and hardenin, based on aws-cli commands -- shell
refunc - Run AWS Lambda on Kubernetes, a Lambda-compatable API -- Golang
s3cmd - Backup to AWS via the command line -- Python
s4cmd - s3cmd with additional features -- Python
Serverless (formerly JAWS) - Javascript + AWS stack, the entire backend is Lambda functions, server-free -- JavaScript
Sneaker - Store secrets on S3 using Amazon KMS -- Golang
ssh2ec2 - SSH into EC2 instances by tag name and/or other metadata filters -- Python pip
StackMaster - Provides a ton of info pre-CloudFormation run so that you know exactly what will change -- Ruby gem
StarCluster - Toolkit for using AWS for high performance computing (HPC), by MIT -- Python
Stout - Easy way to reliably upload a static website to S3, capable of configuring CloudFront and Route 53 -- Golang
Terraforming - Export all AWS resources into Terraform -- Ruby gem
Tools for Amazon Web Services - Amazon's portal for their official tools -- various lang
troposphere - Python library to create CloudFormation descriptions -- Python pip
Zappa - Build and deploy serverless, event-driven Python applications -- Python

Backups

Traditional backup software - see also Cloud File Sync and Sharing

Amanda - The classic -- C perl
Backupninja - Centralize way to configure and schedule many different backup utilities -- shell
BURP (BackUp and Restore Program) - Reduces network traffic and the amount of space required by using librsync -- C
BackupPC - Dedupe and a web GUI for restores -- perl
Backup - Gem for backup and restore, supports tons of platforms and notifiers (RDBMS, S3, Dropbox, rsync, Hipchat, Zabbix) -- Ruby gem
Bacula - Open source backup tool, lots of downloads so I guess it's good I don't know -- C
Back in Time - Similar to TimeMachine, simple GUI backup program -- Python
Bareos (Backup Archiving REcovery Open Sourced) - Fork of Bacula with additional features -- C
borgmatic - A simple wrapper script for the Borg backup software that creates and prunes backups-- Python
bup - Uses the git packfile format, supports global dedupe, can use "par2" redundancy -- Python
DAR (Disk ARchive) - Better than tar, focuses on disks instead of tapes -- C++
ddrecover - This should be the first data recovery tool you use -- C
Deja Dup - GUI for duplicity -- C
Duplicati - Supports encryption and dedupe -- Mono
Duplicity - Encrypted bandwidth-efficient backup using the rsync algorithm -- Python
Elkarbackup - Comes as a ready to use VM, supports Linux and Windows -- PHP
Fpart - Packs file systems into "partitions" so you can do multi-threaded or multi-node rsyncs -- C
FSArchiver - Save the contents of a file system to a compressed archive, if one of the checksums doesn't match the file is lost, not the whole backup -- C
Grsync - GUI for rsync -- Windows OS X C
Mondo Rescue - Disaster recovery, supports tapes, disks, network and CD/DVD as backup media, multiple filesystems, LVM, software and hardware RAID -- C
rdiff-backup - Combines the best features of a mirror and an incremental backup in a bandwidth efficient manner -- Windows OS X Python
Redo Backup and Recovery - Simple bare metal backup and restore, live CD -- Windows
Relax and Recover (REAR) - BMR, simple, integrates with commercial backup solutions -- shell
rsnapshot - Uses rsync and hard links, can keep multiple full backups available while using very little disk space -- OS X perl shell
SafeKeep - Superb project, uses LVM snapshots -- Python
SnapRAID - Backup program that also stores RAID parity information -- C
Unison - Multi-OS file sync tool, syncs from both sides, no master -- OS X
UrBackup - Supports Windows, has a web interface -- Windows C++
ZBackup - Globally deduplicating backup tool -- C
zpaq - Free incremental and journaling command-line archiver -- Windows OS X C++

Chef

Chef gets it's own category because they're MY links - see also Configuration Management

Bento - Chef's collection of baseboxes configured to work with Packer and Vagrant, great for testing -- Ruby
Berkshelf - Like gem bundler for Chef cookbooks, manages dependencies -- Ruby gem
Chake - Tool that helps you manage multiple hosts with chef-solo, think simple mini self-contained Chef (no server) -- Ruby gem
chef-guard - feature rich Chef add-on that protects your Chef server from untested and potentially dangerous cookbooks -- Ruby
chef-vault - Allow specified node(s) to dencrypt the contents of encrypted data bags -- Ruby gem
chef-whitelist - Library that enables easy rollout of changes to one or more hosts, by Etsy -- Ruby
ChefDK (Chef Development Kit) - Includes Berkshelf, Test Kitchen, ChefSpec, Foodcritic, Knife, Chef Zero, Ohai, and more -- Ruby
ChefSpec Examples - A billion code snippets and tests for ChefSpec -- Ruby
Chef Partner GitHub Repos - Official repo for tools, provisioners, and knife plugins from partners (VMware, GCE, Azure, AWS, etc) -- collections
Chef Sugar - Syntactic sugar for Chef by Seth V -- Ruby gem
Chef Supermarket (community) - Official community site for cookbooks -- various lang
Chef Supermarket (self-hosted) - Cookbook repository for Chef, can be hosted internally -- Ruby
Citadel - Cookbook to store secrets in AWS S3 buckets using EC2 and IAM -- Ruby
Foodcritic - Chef linter and static code analysis -- Ruby gem
grocery-delivery - Utility for managing cookbook uploads to distributed Chef backends, by Facebook -- Ruby
Handlers - The official list of community written handlers (Airbrake, IRC, Campfire, etc) -- Ruby
Itamae - CM tool inspired by Chef, but simpler and lightweight, formerly LightChef -- Ruby gem
Inspec - Drop-in replacement for ServerSpec, can be used for audit purposes too -- Ruby gem
knife-backup - Knife plugin to help backup and restore a Chef server -- Ruby gem
knife-push - Official push jobs - action or a command to be executed against a subset of nodes -- Ruby
Knife Plugins - The official list of community written plugins for Knife -- collection
omnibus - Create full-stack installers for your project -- Ruby gem
Policy File - Policyfile is a single document to specify the cookbooks and recipes that should be applied to node(s) -- official experimental
Ridley - Chef API client -- Ruby gem
ServerSpec - RSpec tests for your servers configured by Puppet, Chef or anything else -- Ruby
spiceweasel - Quickly automates the creation of whole Chef environments (batch loading) -- Ruby
Test Kitchen - Automated testing for configuration management tools (mostly Chef) -- Ruby gem

Cloud File Sync and Sharing

Sync files to and share from public or private file stores (think Dropbox, Google Drive, etc) - see also Backups

boar - Stores snapshots of directory trees in a local or remote repository, for BLOBs (pictures, videos , etc) -- Python C
Drive - Push or pull files to Google Drive via the command line -- Golang
git-annex Assistant - Sync folder(s) to any device (NAS, mobile, thumb, cloud, etc) via git -- C OS X mobile
lsyncd - Watches a local directory trees event monitor interface (inotify or fsevents) and kicks off an rsync when things change -- Lua
Mackup - Sync your Mac application settings to various cloud services or git -- Python OS X
Nextcloud - Fork of and replacement for OwnCloud, a self-hosted Dropbox -- various lang Windows OS X
Pydio - Formerly AjaXplorer, AGPL license -- PHP
rclone - Probably the best cloner, supports almost any source and dest -- Golang
Seafile - Also offers a paid professional edition with more features, supports most platforms -- C
SparkleShare - Uses git under the hood, neat -- Windows OS X
Syncany - Supports tons of different protocols for the transfer (SCP, FTP, Samba, S3, etc) -- Gradle
Syncthing - Uses an ID rather than an IP address, share your ID with friends and go -- Golang
Tahoe-LAFS - Free and open decentralized cloud storage system -- Python

Collaboration Tools

ChatOps, code review, groupware, webmail, code sharing, and more - see also Dashboards and Data Visualization and Graphics Stuff and Editors and Git Tools and Software Development Tools

Citadel - Messaging, collaboration tools, and groupware - an all-in-one package -- C
Codeshare - In-browser screenshare to teach coding, group code, or as an interview whiteboard -- in-browser
dev-setup - Automated setup scripts for laptop tools like Sublime Text, AWS, Spark, Android dev, and more -- collection
Etherpad - Enter, save, and share text/code in a web browser -- JavaScript
FreeIPA - Identity, policy, and audit suite, think Active Directory for Linux (LDAP, CA, x509, DNS, Kerberos) -- various lang
FreeMind - OSS mind mapping software, great for brainstorming -- Java Windows OS X
gcalcli - CLI for Google Calendar -- Python pip
gmvault - Export/backup and restore your Gmail account -- Python
Haste / hastebin - Open source pastebin alternative for sharing code, can be installed locally / on-site -- JavaScript
Hubot - Chat bot that can do deploys, look up images, integrate with Google Maps, and tons of other stuff -- CoffeeScript
Isso - A commenting server similar to Disqus -- JavaScript
Kanboard - Simple Kanban board -- PHP
Kolab - Unified communication and collaboration system -- PHP
LDAP Account Manager (LAM) - Full featured LDAP management GUI, can manage almost anything -- PHP
Let's Chat - Self-hosted open source HipChat clone -- JavaScript
Mattermost - OSS Slack alternative -- Golang JavaScript
Mailtrain - Self hosted news letter e-mail app, similar to Mailchimp -- JavaScript
OpenProject - Web-based project management system built on Ruby on Rails -- Ruby
osTicket - Routes inquiries created via email, web-forms and phone calls into a web-based customer support platform -- PHP
OTRS - Open source help desk software -- perl
OwnTracks - Self-hosted location tracking you can share - use for diaries, work orders, etc -- various lang mobile
Pandoc - Convert files from one markup format to another, supports a ton of formats -- Haskell
Phabricator - Suite of web-based software dev collaboration tools, and all-in-one project management tool -- PHP
PrivateBin - Pastebin where the server has zero knowledge of pasted data, data is encrypted/decrypted in the browser using 256 bits AES -- various lang
QueryClips - Pastebin for Postgres or my mySQL SQL query sharing -- in-browser
RainLoop - Simple, modern & fast web-based email client -- PHP
Redmine - Project management webapp -- Ruby
Request Tracker - Bug tracking, help desk ticketing, customer service, workflow processes, change management and more -- perl
Review Board - Code review tool for multiple SCM systems -- Python
Rocket.Chat - OSS Slack clone built with Meteor.js -- JavaScript
Roundcube - Browser-based multilingual IMAP client -- PHP
Say What - Using speech-to-text to fully check out during conference calls -- Python
Scribus - Open source desktop publishing (layout, typesetting, etc), Adobe InDesign alternative -- C++ Windows OS X
SOGo - Groupware that integrates with Microsoft, Android, and Apple products -- Objective-C OS X
Sovereign - Set of Ansible playbooks to deploy a suite of self-hosted apps (mail, colab, calendar, file sync, and more) -- Python
Synergy - Share a single keyboard and mouse with multiple physical computers, only the old version is free now -- closed source Windows OS X
Taiga - Project management web application with agile/ scrum in mind -- Python CoffeeScript
TermRecord - Record and playback terminal sessions, outputs self-contained HTML -- Python
VisioCafe - The largest collection of free Visio stencils -- collection
WeKan - OSS Trello-like kanban board -- JavaScript
YOURLS (Your Own URL Shortener) - Lets you run your own URL shortener a'la TinyURL or bit.ly -- PHP
Zulip - Group chat with chat threads, by Dropbox -- various lang mobile Windows OS X

Configuration Management

OS-level configuration management, Chef has it's own category because - see also Asset Management and Orchestration and Package Patch and Repository Tools

Ansible - CM and orchestration, also can do provisioning -- Python
Ansible Galaxy - Community site for finding, reusing, and sharing Ansible content -- various lang
Automatic Server Hardening - Linux hardening cookbooks/manifests/playbooks for Puppet, Chef, and Ansible -- various lang
awx - Upstream to Ansible Tower - REST API, task engine, etc -- Python
Blueprint - Reverse engineer a server configuration -- Python pip
BOSH - Cloud orchestration, supports Docker containers too -- Ruby
Boxen - Mac / OS X configuration management -- Ruby gem OS X
hiera-eyaml - Backend for Hiera that provides per-value encryption of sensitive data within Puppet yaml files -- Ruby
Jenkins Ansible Tower Plugin - Run Ansible Tower jobs as a build step -- Java
Juju - Ubuntu focused but works on RHEL / CentOS now -- Golang
librarian-puppet - Bundler for Puppet, manages dependencies -- Ruby gem
Oxidized - RANCID replacement, supports many platforms (Cisco, Brocade, Juniper, Citrix, etc) -- Ruby gem
puppet-lint - Check that your Puppet manifest conform to the style guide -- Ruby gem
Puppet Dashboard - Web based dashboard for Puppet -- JavaScript
Puppet Forge - The official community repository of Puppet modules -- collection
puppet-module-skeleton - Skeleton modules for Puppet -- Ruby
r10k - General purpose toolset for deploying Puppet environments and modules -- Ruby gem
RANCID - (Really Awesome New Cisco confIg Differ) - Pulls and saves network device configs and saves them into a CVS, now supports git -- C
Reclass - External node classifier for most CM systems, allows for a tagging system that's a layer above the CM tool -- Python
Rudder - Automation and compliance, uses CFengine -- Scala
Salt / Saltstack - Orchestration, server provisioning, and configuration management -- Python

Containers

Linux containers, container orchestration, networking, Docker, OpenShift, Kubernetes, and related tools - see also Distributed Systems Tools and Virtualization and SDN and Web and HTTP Tools

Alpine Linux - Super minimal BusyBox based Linux distro, perfect for hosting containers -- various lang
Anchore - A centralized service for inspection, analysis and certification of container images -- Golang
appscale - Open source implementation of Google App Engine -- Python
Argo - Container-native workflow engine implemented as a Kubernetes CRD (Custom Resource Definition) -- Golang
Authenticator - A tool for using AWS IAM credentials to authenticate to a Kubernetes cluster -- Golang
Awesome Docker - Massive Docker collection -- collection
Awesome Kubernetes - Collection -- collection
Banzai Cloud - Kubernetes based, open source, multi-cloud with all the good stuff baked in (Prometheus, CICD pipelines, and more) CHECK THIS -- various lang
Buildah - A low-level interface to core-utils, build container images with the scripting language of your choice without using Dockerfiles, compare to Podman -- Golang
cadvisor - Analyzes resource usage and performance characteristics of running containers -- Golang
cert-manager - Automate the management and issuance of TLS certificates from various issuing sources -- Golang
Cilium - Transparently secure layer 7 services, communicate based on identity groups, load balancing, BPF-level for performance and instrumentation & more -- Golang
Clear Linux - New name for Clear Containers, attempts combine the security advantages of VMs with the deployment advantages of containers -- various lang
Click - REPL CLI for Kubernetes -- Rust
Cloud Foundry - Open source PaaS by VMware and Pivotal -- Golang Ruby
CodeReady Containers - Run OpenShift 4.x locally on your laptop, RECOMMENDED -- various lang
CodeReady Single Node Cluster (SNC) - Script to create an OpenShift 4.x single node cluster on Linux using KVM -- shell
Contour - Kubernetes ingress controller using Lyft's Envoy proxy -- Golang
crane - Docker orchestration, similar to Docker Compose -- Golang
ctop - ncurses top-like UI for containers -- Golang
DevSpace - Build, test and run code directly inside any Kubernetes cluster, no more waiting for rebuild + redeploy, run code instantly -- Golang
Dex - A federated OpenID Connect provider -- Golang
distroless - "Distroless" images contain only your application and its runtime dependencies and nothing else, by Google -- various lang
docker-debug - Attach a new "debug container" to existing namespaces so you don't have to include debug tools in the app containers -- Golang
docker-gc - Docker garbage collection of containers and images -- shell
DockerSlim - Uses static and dynamic analysis to create skinny image variants of your fat images -- Golang
dockerviz - Great tool for analyzing images -- Golang
Docker Bench - Checks for dozens of common best-practices around deploying Docker containers in production -- shell
Docker Compose - Define and run multi-container apps with Docker, previously known as fig, official -- Python
Docker Desktop - Notable because it works without admin / root, Mac and Windows -- Golang
Docker Distribution - AKA Docker Registry 2.0 - pack, ship, store, and deliver containers -- Golang
Docker Hub - Official Docker images for many projects -- various lang
Docker Swarm - Docker-native clustering and scaling system, super simple, a good step before jumping to Kubernetes -- Golang
Docker Swarm Visualizer - A visualizer for Docker Swarm using the Docker Remote API, Node.JS, and D3 -- JavaScript
Docker Toolbox - Docker Client, Machine, Compose, Kitematic, VirtualBox, and the boot2docker VM in a single package, official -- various lang
Dockit - Jump into a container image of your choosing, taking all the files from the current directory with you -- shell
Dokku - Docker powered mini-Heroku (PaaS) in around 100 lines of bash -- shell
draft - Streamlined Kubernetes development with sandbox testing & deployment in seconds -- Golang
draino - Automatically drains Kubernetes nodes based on labels and node conditions, can be used for auto-remediation -- Golang
drone - CI platform built on Docker / containers, can also deploy to Kubernetes -- Golang
dumb-init - Minimal init system for containers, by Yelp -- C
EdgeFS - Rook plugin that provides NFS, S3, and iSCSI volumes to containers via a Kubernetes operator, integrated with Kubernetes CSI -- Golang
Eirini - Kubernetes backend for Cloud Foundry -- Golang
Escalator - Batch or job optimized horizontal autoscaler for Kubernetes -- Golang
Fabric8 - Open source microservices platform based on Docker, Kubernetes and Jenkins -- Java
Fedora CoreOS - The best of CoreOS + Fedora Atomic Host, upstream to RHEL CoreOS, successor to now sunset RHEL / Fedora Atomic & Container Linux -- various lang
Flannel - Network fabric for containers via etcd, designed for Kubernetes -- Golang
Fluent Bit Kubernetes Daemonset - The best logger, super light weight -- Golang
Flux - Tool that automatically ensures that the state of a Kubernetes cluster matches the config in git via Kubernetes operators -- Golang
Flynn - PaaS built on top of Docker, can run stateful services -- Golang
Gangway - Enable authentication flows via OIDC (OpenID Connect Tokens) for a Kubernetes cluster -- Golang
Gitkube - Build and deploy docker images to Kubernetes using git push -- various lang
GKE On-prem - An on-premise version of Google Kubernetes Engine, currently in beta -- Golang
gravity - Creates snapshots of a Kubernetes cluster that can be restored elsewhere (on-prem, DR situation, etc) -- Golang
gvisor - User-space kernel, can be used to sandbox containers, by Google -- Golang
Helm - tool for managing Kubernetes charts (packages of pre-configured Kubernetes resources) -- Golang
helm-value-store - Manage working with multiple values.yaml files for nearly identitcal deployments -- Golang
Heptio Sonobuoy - Kubernetes end to end conformance testing and debugging tool -- Golang
img - Standalone, daemon-less, unprivileged Dockerfile and OCI compatible container image builder -- Golang
Istio Operator - An operator that manages Istio deployments on Kubernetes, by Banzai Cloud -- Golang
Jenkins Docker Slaves Plugin - Aka Dockins, execute a Jenkins job inside one or more containers, supports most job types -- Java
Jenkins Kubernetes Plugin - Use a Kubernetes cluster to dynamically provision a Jenkins agent (using Kubernetes scheduling mechanisms to optimize the loads), run a single build, then tear-down that agent -- Java
Jenkins X - Another Kubernetes deployer -- various lang
jib - Build container images for your Java applications, by Google -- Java
k3s - Lighweight Kubernetes in a 40mb binary, built for the edge or laptop or Pi, by Rancher -- Golang
k8s-prom-hpa - A Kubernetes horizontal pod autoscaler with Prometheus custom metrics -- Golang
Kata Containers - A mix of Clear Containers / Clear Linux and Hyper's runV -- frankencontainers various lang
Keel - Stateless, automated Kubernetes deployment updates -- Golang
Kind - Run local Kubernetes clusters using Docker container “nodes", great for local development -- Golang
Kismatic - Set of production-ready defaults and best practice tools for creating enterprise-tuned Kubernetes clusters, supports bare metal. -- Golang
Kitematic - GUI Docker management on Mac & Windows (laptops), official -- JavaScript Windows OS X
Kong - Microservice abstraction layer (aka API Gateway or Service Mesh), great for creating API endpoints -- Lua
kops - CLI for managing, upgrading, maintaining, creating, etc Kubernetes clusters -- Golang
Kraken P2P Docker registry capable of distributing TBs of data in seconds using a slightly modified BitTorrent protocol -- Golang
kubeadm-aws - Really cheap Kubernetes cluster on AWS with kubeadm -- Terraform
kubeadm-dind-cluster - kubeadm and DIND (Docker in Docker) create a multi-node Kubernetes cluster on your laptop for dev -- Shell
kube-applier - service that enables continuous deployment of Kubernetes objects by applying declarative configuration files from a Git repository to a Kubernetes cluster -- Golang
kube-bench - Compliance checker for Kubernetes CIS benchmarks -- Golang
kube-hunter - Hunt for security weaknesses in Kubernetes clusters -- Python
kube-prometheus - Use Prometheus to monitor Kubernetes and applications running on Kubernetes -- Golang
kube-spawn - A tool for creating multi-node Kubernetes clusters on a Linux machine using kubeadm & systemd-nspawn -- Golang
Kubecost - Creates cost future and past models so you can see and predict your spend -- Golang
kubectx - Easily switch between kubectl contexts and namespaces, also includes the kubens tool -- Ruby
kubed - Perform periodic cluster snapshots, provide temp storage for deleted objects, automatic event forwarding, deliver notifications via various channels for Kubernetes -- Golang
kubediscovery - Tool that helps you find dynamic composition tree of Kubernetes objects -- Golang
KubeEdge - CNCF project to run Kubernetes at edge -- Golang
kubehost - Uses existing features of GKE to expose your service directly onto one of the VMs -- shell
kubeprovenance - Track chronology of declarative operations performed on custom resources to understand how these operations affect underlying platform elements, amazing historical auditing and reporting tool -- Golang
Kubernetes - Open source orchestration system for Docker containers, by Google -- Golang
kubernetes-cloudflare-sync - Run in your Kubernetes Cluster on GKE and sync DNS records on Cloudflare with your nodes IPs to avoid GCP LB fees -- Golang
kubernetes-deploy - tool that helps you ship changes to a Kubernetes namespace and understand the result, by Shopify -- Ruby
Kubernetes IN Docker (KinD) - Tool for running local Kubernetes clusters using Docker container "nodes" -- Golang
Kubernetes Network Policy Recipes - Example recipes for Kubernetes Network Policies that you can just copy paste -- collection
kubespray - Deploy a production ready Kubernetes cluster, a Kubernetes Incubator project -- Golang
kubewatch - Kubernetes event watcher and handler (currently only publishes to Slack channels, integrations wanted!) -- Golang
Kube Forwarder - GUI Kubernetes port forwarding manager -- JavaScript
kubicorn - Multi-provider deployment abstraction layer / library for Kubernetes -- Golang
kustomize - The preferred templating tool, now built-in to kubectl, official -- Golang
LinuxKit - Toolkit for building custom minimal, immutable Linux distributions -- Golang
Logspout - Log router for Docker containers -- Golang
Lokomotive - Kubernetes distribution with baked in multi-cloud and Terraform support, by Kinvolk -- various lang
Magic Namespace - Helm chart for managing security between namespaces, great for multitenant clusters -- YAML
memcached-operator - A Kubernetes operator for memcached, good to use as an Operator example too -- Golang
MetalKube - Bare metal provisioning for Kubernetes, by Red Hat -- Golang
MetalLB - Load balancer for bare metal Kubernetes clusters, by Google -- Golang
Microk8s - Alternative to minikube, by Canonical -- shell
minikube - Kubernetes environments on your laptop -- Golang
Minishift - OpenShift in a VM for testing / learning -- Golang
ngnix-proxy - Nginx proxy for Docker containers using docker-gen, recommened -- Python
oc-cluster-up - Docker container to launch a multi-node, docker-in-docker OKD 4.x cluster -- shell
Octant - Web based representation of a Kubernetes cluster, by VMware -- various lang
OKD - The upstream for Red Hat's OpenShift 3.x, previously OpenShift Origin -- Golang
OKD Install - Set of file that installs OKD 3.x (OpenShift's upstream, formerly OpenShift Origin) on a single CentOS VM for testing & dev -- shell
OpenShift Container Platform Install Demo - Install an OpenShift 4.x demo system on Linux, Windows, or Mac, by Red Hat -- various lang
Panamax - Containerized app creator with an open-source app marketplace hosted in GitHub -- various lang
pipework - SDN for Linux Containers -- various lang
Popeye - Scans the live cluster for dead or unused resources such as ports mismatches, metrics utilization, probes, container images, RBAC rules, naked resources, etc -- Golang
Portainer - Web interface for Docker aka us-for-docker -- JavaScript
Prometheus Operator - Creates/configures/manages Prometheus clusters atop Kubernetes -- Golang
pulumi - HOT create and deploy cloud programs that use containers, serverless functions, hosted services, and infrastructure, on any cloud, supports most languages -- various lang
Rancher - Provides a complete platform for operating Docker in production -- various lang
Registrator - Service registry bridge for Docker, supports Consul, etcd -- Golang
rkt (Rocket) - New container system by the CoreOS guys -- Golang
Rocker - Adds new instructions to the Dockerfile instruction set for smaller images and faster builds -- Golang
Rook - Self managing, self healing storage orchestrator for Kubernetes via an operator plugin, see also EdgeFS -- Golang
Security Goals - Compliance checking and reporting for Kubernetes based applications, by the Canadian Digital Service -- various lang
skaffold - Easy and repeatable Kubernetes development, test locally then push to a cluster, by Google -- Golang
Spinnaker - Cloud-focused CI/CD system for immutable infrastructure, by Netflix -- Python
Squash - Debug applications from your terminal or IDE while they run in Kubernetes or OpenShift (locally or remotely) -- Golang
swarm-viz - Docker Swarm visualizer -- JavaScript
Tectonic Installer - Install an opinionated Kubernetes cluster the "Tectonic Way", a sane predefined deployment and workflow -- various lang
Telepresense - Local development against a remote Kubernetes or OpenShift cluster -- Python
Teleport - Auditing bastion host & middleman, now supports the Kubernetes apifserver protocol -- Golang
Terraform Operator - Use Kubernetes to run Terraform, by Rancher -- Golang
Tsuru - Docker-based PaaS -- Golang
Tubekit - kubectl wrapper with powerful yet context switching and pattern matching -- Golang
Typhoon - Minimal and free Kubernetes distro, great for testing and learning on small systems -- various lang
Watchtower - Monitors your running Docker containers and restart them when a new image is available -- Golang
Weave - Virtual network that connects Docker containers deployed across multiple hosts -- Golang
Wormhole - CNI plugin for Kubernetes that uses WireGuard for creating a full mesh encrypted network between each host in the Kubernetes cluster. The Kubernetes API is used to coordinate key exchange and configuration -- Golang
Vault Secrets Operator - Kubernetes operator for Hashicorp Vault -- Golang
Velero - Manage disaster recovery for your Kubernetes persistent volumes and cluster resources, formerly Heptio Ark -- Golang
virtlet - Kubernetes CRI implementation for running VM workloads (QCOW2 images) -- Golang
virtual-kublet - kublet implementation that masquerades as a kubelet for the purposes of connecting Kubernetes to other APIs (Fargate, ACI, IoT, Nomad, Azure, etc) -- Golang
Voyager - HAProxy backed secure L7 and L4 ingress controller for Kubernetes -- Golang

Dashboards and Data Visualization

Dashboards for monitoring, alerting, metrics, data visualization tools, and status boards - see also Metrics and Time Series Data and Logging and Monitoring and Alerting

Bigdesk - Live charts and statistics for Elasticsearch cluster -- JavaScript
Cachet - Create beautiful, responsive status pages -- PHP
Cacti - Web-based network monitoring and graphing tool designed as a front-end to RRDtool -- PHP
CactiEZ - Super simple, added features, works right out of the box -- PHP
Dashing - The exceptionally handsome dashboard framework, no longer maintained, successor is Smashing -- Ruby gem
Dashing Widgets - Massive collection of widgets for Dashing -- collection
Facette - Time series data visualization and graphing software -- Golang
Flame Graphs - Stack trace visualizer by Brendan Gregg -- perl
Gource - Software version control visualization tool -- C++
Graphene - Graphite dashboard in D3 and Backbone -- JavaScript
Graphiti - Graphite dashboard using Ruby and Redis -- Ruby
Hygieia - Visualize near real-time status of the entire delivery pipeline, by Capital One -- Java
Hystrix Dashboard - Dashboard for Netflix's Hystrix tool -- Java
Kibana - Visualization component of the ELK stack -- JavaScript
ksar - Creates pretty graphs from sar output -- Java
logstalgia - Web site access log visualization tool, aka Apache Pong -- C++
lsofgraph - lsof output into to Graphviz -- Lua
Grafana - Modern dashboard for Graphite -- JavaScript
grafana-statusmap - Grafana status panel -- JavaScript
Mozaik - Create beautiful dashboards using Node/React/D3 -- JavaScript
MRTG (Multi Router Traffic Grapher) - Still being updated -- perl
Nagdash - Dashboard / NOC screen for Nagios -- PHP
NagVis - Visualization suite for Nagios -- PHP
Nagiosgraph - Another visualization tool for Nagios data -- perl
Network Weathermap - Network visualization tool, create a "weather map" just like big ISPs use, not dead yet -- PHP
pdash - web dashboard for linux using data mainly served by psutil -- Python pip
PNP4Nagios - Analyzes performance data provided by plugins and stores them automatically into RRD-databases -- PHP
promviz - Visualize the traffic of your clusters in realtime from Prometheus data -- Golang
redash - Web application that allows to easily query an existing database, share the dataset and visualize it in different ways -- various lang
ServerStatus - Display and monitor your servers statistics in a beautiful way -- C C++ JavaScript
Seyren - Alerting dashboard for Graphite -- Java
Smashing - Successor to Dashing -- Ruby
Stashboard - Status dashboard for APIs and software services, requires Google App Engine -- Python
Staytus - Complete solution for publishing the latest info about issues with your web applications, networks or services -- Ruby
Tasseo - Dashboards using D3, HTML5, Bootstrap, and others -- JavaScript CoffeeScript
Tessera - Graphite dashboard in Python -- Python pip
Thruk - Web interface for Nagios, Icinga, Shinken and Naemon, can create SLA reports, has a mobile client -- JavaScript
Uchiwa - Dashboard for Sensu -- Golang
vnstati - Creates PNG images using vnStat data -- built-in

Distributed Systems Tools

DCOSes, microservices, service discovery, schedulers, Mesos, and related tools for dynamic, warehouse-scale computing - see also Containers and HPC Tools

Akkio - Data placement service that determines how and when to move information in order to optimize retrieval speed for people across the globe, using the minimum required number of copies -- various lang
Ambassador - Kubernetes-native API gateway built on Envoy proxy includes gRPC, auth, TLS, and more -- Python
Aurora - Mesos scheduler for long running services and cron jobs, similar to Marathon -- Java
Avro - Data serialization system with backwards compatible schemas -- Java
Bamboo - HAProxy auto configuration and auto service discovery for Mesos and Marathon -- Golang
Chaperone - End-to-end Kafka auditing (data loss, latency, message duplication, etc), by Uber -- Java
Chronos - Distributed, fault tolerant cron scheduler that runs on top of Apache Mesos -- various lang
confd - Manage local application configuration files using templates and data from etcd or consul -- Golang
Cruise Control - Fully automate the dynamic workload rebalance and self-healing of a Kafka cluster, by Linkedin -- Java
Cruise Control UI - Also by Linkedin -- JavaScript
consul - Service discovery and configuration via DNS or HTTP, great for auto-scaling -- Golang
consul Tools - Official, includes consul-template and others -- various lang
Curator - ZooKeeper client wrapper and rich ZooKeeper framework, by Netflix -- Java
DC/OS - Pre-configured data center OS distribution that includes Mesos, Marathon, AdminRouter, and more -- Python
DoctorKafka - Kafka cluster auto healing and workload auto-balancing -- Java
Envoy Proxy - Sidecar container for distributed applications or microservices, data plane service mesh / edge proxy -- C++
etcd - Distributed, consistent key-value store for shared configuration and service discovery -- Golang
eureka - AWS Service registry for resilient mid-tier load balancing and failover, by Netflix -- Java
fabio - Zero-conf load balancing HTTP(S) router for deploying microservices managed by Consul, by eBay -- Golang
Flink - Next-generation true stream processing platform for real-time analytics -- Java
Gloo - Gateway / abstraction layer between upstream services, based off of Envoy -- Golang
GraphQL - Alternative to REST, allows clients to define the structure of the data, subscribing to data flows, and more -- various lang
Hystrix - Library to stop cascading failures -- Java
Ignite - General-purpose in-memory platform for in-memory computing use cases -- Java
Istio - Envoy + auth, policy enforcement, telemetry, traffic flow management etc control plane that runs on top of Mesos and Kubernetes, service mesh control plane -- various lang
jespen - A framework for distributed systems verification, with fault injection -- Clojure
JVM Profiler - Distributed profiler to collect JVM performance and resource usage metrics and serve them for further analysis, by Uber -- Java
Kafka - Stream processing platform (logs, IoT metrics, anything) -- Java
linkerd2 - The project formerly known as Conduit has been merged into this -- Golang
LogDevice - A distributed data store for logs, by Facebook -- C++
Mantl - Complete microservices infrastructure built using OSS tools by Cisco -- various lang yowza
Marathon - Mesos scheduler for "always on" jobs (eg: web services) -- Scala
MaxScale - General purpose DB query proxy, router, and load balancer, by MariaDB -- C
mcrouter - memcached protocol router for scaling memcached, by Facebook -- C++
Mesos - Cluster manager and scheduler, similar to Google's Borg and Omega projects -- C++
mesos-consul - Automatically registers/deregisters services run as Mesos tasks -- Golang
Mesosphere - Apache Mesos schedulers for almost anything, commercial support is available -- C++
miniMesos - Spin up Mesos clusters on your OS X laptop, can be used for TDD too -- Java
Mitogen - Python library for writing distributed self-replicating programs like magic -- Python
Nomad - Highly scalable application, process, and container scheduling tool, multi-cloud support -- Golang
nsq - Realtime distributed messaging platform / message queue -- Golang
OpenStack - Private cloud -- Python
Pinpoint - Application Performance Monitoring (APM) for distributed systems, based on Dapper -- Java
Pulsar - A Kafka alternative, by Yahoo -- Java
redis-cell - Redis module that provides rate limiting in Redis as a single command using GCRA -- C
Redisson - Distributed and scalable Java data structures on top of Redis -- Java
Riemann - Aggregates events from your servers and applications with a powerful stream processing language, for distributed systems, similar to Borgmon -- Clojure
Ringpop - Fault tolerant application-level sharding for Golang or Javascript -- JavaScript Golang
Serf - Decentralized solution for service discovery and orchestration -- Golang
SkyDNS - Service discovery via DNS for etcd -- Golang
Spark - Near real-time analytics processing platform, succeeded by Flink (real streaming vs Spark's microbatches) -- various lang
Spring Cloud Config - Allows Java Spring to read config info from service discovery or similar source -- Java
Status - Report the current state of external systems that an application depends on, as well as the current health of any internal aspects of the application, by Indeed -- Java
SuperGloo - Service mesh management and orchtestration -- Golang
Synapse - Service discovery framework by Airbnb -- Ruby
uReplicator - Improved Kafka MirrorMaker by Uber -- Java
vulcand - Programmatically extendable proxy for microservices and API management -- Golang
Zookeeper - Distributed configuration service, synchronization service, and naming registry -- Java

Editors

IDEs, text & source editors, vim plugins, and similar tools - see also Graphics Stuff and Collaboration Tools

010 Editor - Professional hex editor that supports binary templates for easy reading, scripting, and more -- closed source
activate-power-mode - Activate POWER MODE and write code in style, an Atom plugin -- CoffeeScript
Atom - Superb text editor, created by GitHub -- CoffeeScript
Atom Vim Mode - vi/vim style controls for Atom -- CoffeeScript
Atom Linters - A collection of lint tools for the Atom editor -- various lang
Brackets - Modern editor that understands and focuses on web design, by Adobe -- JavaScript
LargeFile - vim plugin that automatically disables certain things so you can edit large (multi-gig) files faster -- vim
Light Table - Next-generation editor that gives you instant feedback -- Clojure
livedown - Live, in-browser markdown previews for vim and Sublime -- various lang
MacDown - Markdown editor and live preview for Mac -- Objective-C OS X
MacVim - Has far more features than the vim that's included with the OS -- C
Nuclide - Collection of packages for Atom to provide IDE-like functionality for a variety of programming languages and technologies, by Facebook -- JavaScript
Notepad++ - Killer GPL'ed text editor for Windows -- C++
percol - Interactive grep (search) tool -- Python
Powerline - Provides various statues on the bottom of your session, flexible -- Python
Textmate - GUI text editor for OS X -- C++
UltiSnips - The ultimate snippet solution for vim -- Python
vim-json - A better JSON plugin for vim -- vim
vim-snippets - snipMate & UltiSnip snippets -- vim
Vimium - Chrome extension that provides vi/vim style shortcuts for navigation and control -- CoffeeScript Chrome
Vundle - Popular plug-in manager for vim -- vim
wasavi - vim/vi controls in browser text areas -- JavaScript Firefox Chrome
wxHexEditor - Free hex editor, disk editor, and big file editor for Linux, Windows and Mac OS X -- C
YouCompleteMe - Fuzzy-search code completion engine for vim -- Python

Git Tools

Tools for interacting with git and GitHub - see also Software Development Tools

BFG Repo-Cleaner - Scrub large blobs and sensitive data from git history -- Scala
blackbox - Safely store secrets in Git, by Stack Exchange -- shell
Completion - Shell tab completion for git branch names -- shell
Gerrit - Web based code review and repo management for Git -- Java
git-fat - Like git-media but without the Ruby dependencies -- Python
GitKraken - Probably the best multi-platform git GUI -- closed source Windows OS X Linux
GitHub Pull Request Builder Plugin (gprbp) - Jenkins plugin that allows certain comment strings to kick off builds or take other actions -- Java
GitLab - Kinda like an open source GitHub, has both a community and paid version -- Ruby
GitLab CI - CI that integrates with GitLab -- Ruby
GitRob - Scan repos for sensitive information -- Ruby
gitsome - Supercharged CLI with GitHub integration -- Python
GitUp - Maybe the best git GUI -- Objective-C
gitwatch - Automatically commit changes when specified files or directories are modified -- shell
Git Interfaces, Frontends, and Tools - Massive list on the official kernel.org wiki -- various lang
Gogs - Painless, self-hosted Git service written in -- Golang
hub - Official CLI for GitHub -- Golang
myrepos - Flexible tool for managing many repos -- perl
Signing - Sign commits and/or tags using GPG keys to verify the identity of the commiter -- built-in

Graphics Stuff

Not everything happens in the browser or on the command line - see also Collaboration Tools and Data Visualization and Dashboards

Avidemux - Simple, all-in-one, GUI video editor and converter -- C++ Windows OS X
Blender - 3D graphics software for animated films, visual effects, art, 3D printed models, and more -- C Python Windows OS X
blockdiag - Generate simple block/sequence/activity/network diagrams from text files -- Python pip
Darktable - Photography workflow application and RAW developer, Adobe Lightroom replacement -- C OS X
draw.io - Free online flow chart maker / Visio alternative, can be self-hosted -- in-browser
GlyphSearch - Search for icons from Font Awesome, Glyphicons, IcoMoon, Ionicons, and Octicons -- collection
GIMP (GNU Image Manipulation Program) - Open source Adobe Photoshop replacement -- C
Graphviz - Graph visualization and flow chart software -- wacky license
Greenshot - The best Windows screenshot tool -- C# Windows
Inkscape - Open source vector image editor, Adobe Illustrator replacement -- C C++ Windows Mac
LICEcap - Capture an area of your desktop and save it to a GIF -- C Windows OS X
mac2imgur - Auto-upload screenshots to Imgur -- Swift OS X
maim - The most powerful and flexible Linux desktop screenshot tool -- various lang
Media Player Classic - Home Cinema (MPC-HC) - Open source media player for Windows -- C++ Windows
OpenShot - Video editing software, 2.0 will support other additional platforms -- Python Windows OS X
Origami - Interactive UI design prototyping without programming, by Facebook -- various lang
Pencil - Open source GUI prototyping and mockup tool, supports all platforms -- Windows OS X
PlantUML - Easily create beautiful UML Diagrams from simple textual description -- Java
ScreenToGif - Record a selected area of your screen, edit and save it as a GIF or video -- C++
ShareX - One of the best screenshot/screencast capture and sharing tools for -- Windows OS X
Skitch - Feature-rich screenshot editing, sharing, and annotation tool Mac/OS X -- closed source
VLC Media Player - Media (music, video, etc) player and streaming server -- C Windows OS X
yEd Graph Editor - Flowcharts and UML diagrams -- closed source

High Availability Clustering Tools

HA clustering tools including storage replication, failover, VIPs, and more - see also Distributed Systems Tools and Containers

AN! Cluster Tutorial 2 - Building clusters with OSS software, very detailed -- article
Cluster Manager (cman) - Clustering framework that's built into RHEL/CentOS/Fedora -- built-in
Corosync - HA framework and cluster engine -- C
csync2 - General purpose cluster file sync tool -- C
DRBD (Distributed Replicated Block Device) - Mirror block devices to a remote system aka replication -- C
Ganeti - Wrappers around existing tools to make it easy to create HA clusters, by Google -- Python
HAproxy - Open source software load balancer -- C
haproxyctl - Wrapper to talk to the HAProxy socket, as well as regular init (start stop restart) shit -- Ruby
keepalived - Load balancing and high availability -- C
huptime - Zero downtime restarts of unmodified programs -- C
Linux-HA - Building blocks for high availability systems -- wiki-and-collection
LVS (Linux Virtual Server) - Linux-based load balancer, also includes the IPVS kernel module -- C
Multibinder - Simple Ruby daemon that makes true zero downtime reloads simple, by Github -- Ruby
Pacemaker - HA resource manager -- C
rcron - cron redundancy and failover, ensures a job will only run on the "active" machine -- lost-to-the-internet C
rmanager - Resource group manager daemon for cluster services -- built-in
Seesaw - Load balancer based on Linux Virtual Server (LVS), by Google -- Golang
Traefik - Modern HTTP reverse proxy and load balancer, supports many backends -- Golang
UCARP - VIP management using the CARP protocol -- C

HPC Tools

High performance computing for simulations, supercomputing, shared memory systems, and grid computing - see also Distributed Systems Tools and Containers

Clustered File System - Ceph, GlusterFS, Lustre, etc, take your pick -- various lang
HTCondor - Workload management system for compute-intensive jobs, formerly Condor
Maul Cluster Scheduler - Precursor to the Moab HPC Suite
MPI for Python (mpi4py) - Python bindings for the Message Passing Interface (MPI) standard
MPICH - High-performance and widely portable implementation of the Message Passing Interface (MPI) standard
MUNGE - Authentication service for creating and validating credentials, designed for HPC
MVAPICH2 - MPI-3 over OpenFabrics-IB, OpenFabrics-iWARP, PSM, and TCP/IP
OpenMP - API that supports multi-platform shared memory multiprocessing programming in C, C++, and Fortran -- article
OpenMPI - Popular Message Passing Interface (MPI) library -- C
Open Grid Scheduler - Formerly known as Sun Grid Engine -- C
OSCAR (Open Source Cluster Application Resources) - Makes it easy to create a Beauwulf-type HPC cluster
Rocks Cluster Distribution - Linux cluster distribution that enables end users to easily build computational clusters, grid endpoints and visualization displays
Slurm (Simple Linux Utility for Resource Management) - One of the mostly widely used schedulers
StarCluster - Toolkit for using AWS for HPC, by MIT -- Python
TORQUE (Terascale Open-source Resource and QUEue Manager) - An updated and extended version of Portable Batch System (PBS)

Live CD Tools

Security, recovery, bootable USB/CD/DVD creation tools, diagnostics, and more - see also Security Tools and Backups and Provisioning Tools

BlackArch Linux - Penetration testing Linux distro, based off of Arch Linux -- various lang
Buscador - Live CD Linux distro preconfigured for online investigators -- various lang
CAINE (Computer Aided INvestigative Environment) - Computer forensics on a live CD -- various lang
DBAN (Darik's Boot and Nuke) - Spinning disk wiper -- various lang
Easy2Boot - Create multiple bootable Linux ISOs on the same USB drive -- Windows
GParted Live - Small, bootable ISO that contains gparted - great for resizing a non-LVM root file system -- C
Hiren's Boot CD - Re-adding, updated after 6 long years -- closed source
Kali Linux - Penetration testing Linux distro -- various lang
Network Security Toolkit (NST) - Live CD that includes most tools in insecure.org's top 125 tools list -- various lang
NirLauncher - USB live distro that contains all of the NirSoft utilities and more, essential for Windows -- closed source Windows
PALADIN - Easy to use Linux-based live CD for forensic analysis -- various lang
Rufus - Create bootable USB flash drives -- Windows
Security Onion - Linux distro for IDS, NSM, and log management -- various lang
Stresslinux - Hardware burn-in and stress testing -- various lang
System Rescue CD - System recovery CD that focuses on Linux system recovery -- various lang
Tails - Aims at preserving your privacy and anonymity via Tor -- various lang
Ultimate Boot CD (UBCD) - Tons of x86 diagnostic and stress test tools on a single CD -- closed source Windows
UNetbootin - Create custom, bootable USB Linux CDs -- Windows OS X
YUMI - Multiboot USB creator, Linux and -- Windows

Logging

Log management, analysis, analytics, and collection from any source - see also Data Visualization and Dashboards and Metrics and Time Series Data and Monitoring and Alerting

Adiscon LogAnalyzer - Slick web interface for syslog messages -- PHP
Countly - Mobile and web analytics and marketing platform -- JavaScript
Elastalert - Send alerts based on ElasticSearch logs (http 500 increase/spike, any custom string, etc) -- Python
ElasticDump - Import / export tools for Elasticsearch -- JavaScript
ElasticHQ - Does not yet support ES 5.x -- JavaScript
Elasticsearch - Component of the ELK stack, used for super fast searches -- Java
Elasticsearch Exporter - Script to import/export data from ElasticSearch to various other storage systems -- JavaScript
Errbit - Self-hosted error catcher, Airbrake API compliant -- Ruby
Filebeat - By Elastic, the next generation Logstash Forwarder -- Golang
fluentbit - Fast and lightweight log processor, part of the fluentd family -- C
Fluentd - Unified logging layer, often used with Kubernetes / OpenShift / containers -- Ruby gem
Flume - Distributed, reliable, and available service for efficiently collecting, aggregating, and moving large amounts of log data -- Java
GoAccess - Real-time web log analyzer and interactive viewer that runs in a terminal and/or dashboard -- Windows OS X
Graylog2 - Log capture and analysis -- various lang
IRCcat - Send log messages and alerts to an IRC channel, can also use IRC to send commands -- Java
lnav - Advanced log file viewer for the small-scale, terminal/ncurses based -- C++
Log Courier - Enhanced fork of Logstash Forwarder -- Ruby
Logagent - Lightweight log shipper, like Filebeat and Logstash in one without the JVM footprint -- JavaScript
Logplex - Distributed syslog log router, uses Redis, by Heroku -- Erlang
logstash - Collect, parse, and store logs. A component of the popular ELK stack -- Ruby
Logster - Utility for reading log files and generating metrics to configurable outputs by Etsy -- Python
Logwatch - Monitor logs and send an e-mail when event(s) occur -- perl
Mamomo - Web analytics platform with a killer UI, formerly PIWIK -- PHP
multilog - Reads a sequence of lines from stdin and appends selected lines to any number of logs -- DJB
multitail - Monitor multiple log files in a single terminal window -- C
netconsole - Kernel module that sends kernel log messages (dmesg, etc) to a remote system without using syslog -- C
NXLOG - Universal log collector and forwarder, supports many formats/platforms/sources including Windows -- C Windows
Open Web Analytics (OWA) - Track and analyze how people use your websites and applications -- PHP
Sentry - Application exception logging -- Python
Snoopy Logger - Logs commands that are executed and saves the information to syslog -- C
Snowplow - Web, mobile and event analytics -- Scala
swatch - Simple log watcher -- built-in
Webalizer - Web and FTP log analyzer -- C

Metrics and Time Series Data

Collection, analysis, and storage of metrics, telemetry, and instrumentation data from almost any source - see also Dashboards and Data Visualization and Monitoring and Alerting and Logging

Banshee - Real-time anomalies detection system for periodic time series -- JavaScript
collectd - Collects system performance statistics -- C
collectd Related Sites - Great tools that integrate with collectd -- collection
collectl - sar on steroids -- C
Cortex - Multitenant, horizontally scalable Prometheus as a Service -- Golang
Diamond - Python daemon that collects system metrics and publishes them to Graphite (or similar), has an API -- Python
dim_STAT - Collects almost everything and stores it in a MySQL database, produces reports too -- C
FastForward - Flexible system event and metric forwarding agent by Spotify -- Ruby gem
Ganglia - Focused on HPC / distributed clusters, uses RRD -- various lang
Graphite - Store numeric time-series data and render graphs of the data on demand -- Python
Graphite Tools - Tools that work with Graphite -- collection
Heka / hekad - Stream processing, can gather logs or performance metrics, by Mozilla, based on Borgmon -- Golang
InfluxDB - Distributed time series database with no external dependencies -- Golang
jmxtrans - Connector between speaking to a JVM via JMX and whatever stats / TSDB you use -- Java
KairosDB - Time series DB written on top of Cassandra -- Java
m3 - Distributed TSDB and query dngine, Prometheus sidecar and metrics platform by Uber -- Golang
Metricbeat - fetches a set of metrics on a predefined interval from OS & services and ships them to Elasticsearch or Logstash -- Golang
Metrics - Metrics and instrumentation at both the JVM and application level -- Java
Micrometer - Provides a simple facade (fake interface) over the instrumentation clients for the most popular monitoring systems, allowing you to instrument your JVM-based application code without vendor lock-in -- Java
mtail - Extract monitoring data from application logs for collection into a timeseries database, by Google -- Golang
OpenTSDB - Store and serve massive amounts of time series data without losing granularity -- Java
Prometheus - Metrics collection and storage, can trigger alerts when thresholds are breached, based on Borgmon -- Golang
prometheus-am-executor - HTTP server that receives alerts from the Prometheus Alertmanager and executes a given command with alert details set as environment variables -- Golang
Sensu - Open source monitoring framework, cloud-focused, dynamic, scalable - also does metrics collection -- Ruby
Skyline - Real-time anomaly detection system to enable passive monitoring of metrics without the need to configure thresholds -- Python
SNMPcollector - SNMP collector that saves into InfluxDB for easy visualization -- Golang JavaScript
SNMP MIB Archive - Massive archive of SMMP MIBs, please fork and contribute -- collection
StatsD - Network daemon that listens for stats/counters/metrics and sends them to backend services (TSDB, Graphite, etc), by Etsy -- JavaScript
Telegraf - Agent for collecting, processing, aggregating, and writing metrics -- Golang
Thanos - Highly available Prometheus setup with long term storage capabilities -- Golang
TimescaleDB - PostgreSQL extension for time series ingestion and queries via SQL -- C
Whisper - Store time series info in regular file system files, a modern RRD -- Python

Monitoring and Alerting

Monitor stuff, send alerts, wake you up - see also Metrics and Time Series Data and Logging and Data Visualization and Dashboards

Adagios - Web based Nagios configuration interface -- HTML
Alerta - Distributed and de-coupled, requires MongoDB -- Python
Bosun - Monitoring and alerting system written by Stack Exchange, based on Borgmon -- Golang
Cabot - Self-hosted, easily-deployable monitoring and alerts service - like a lightweight PagerDuty -- Python
check_mk - Extensions / plugins for Nagios -- C
check_mk Multisite - GUI for check_mk -- various lang
Daemon Tools - Service monitoring and management tools -- DJB
FastForward (ffwd) - Flexible system event and metric forwarding agent by Spotify -- Ruby gem
health - An easy to use, extensible health check library for Go applications -- Golang
Icinga - Nagios fork, updated frequently -- various lang
Icinga2 - Complete re-write of Icinga by the same folks -- various lang
LibreNMS - GPL fork of Observium -- various lang
Monit - Includes tools to automatically take action when certain conditions are met (eg: restart a process when it dies) -- C
Monitorix - So lightweight that it can be used in mobile devices, aka Mikaku -- perl
Naemon - Modular Nagios fork -- various lang
Nagios - One of the most widely used OSS monitoring programs -- various lang
nagios-herald - Gives context to Nagios alerts, by Etsy -- Ruby
Nagios Exchange - Centralized repository of Nagios plugins, addons, extensions, etc -- collection
NetXMS - Monitoring for all types of devices across the entire data center (hosts + network devices) -- C
OpenNMS - Network monitoring, also supports configuration/asset management -- various lang
Open Monitoring Distribution (OMD) - Nagios bundled with the most popular plugins and tools -- various lang
pmacct - IP and network traffic accounting / monitoring -- C
PHP Server Monitor - Simple monitoring package that can use built-in public SMS gateways for notifications -- PHP
Sensu - Open source monitoring framework, cloud-focused, dynamic, scalable - also does metrics collection -- Ruby
Sensu Plugins - Official community site for Sensu plugins -- various lang
Shinken - Nagios-compatible monitoring, supports high availability -- Python
Tattle - Self service alerting and dashboard frontend for Graphite and Ganglia -- PHP
Uptime - Remote monitoring application using Node.js, MongoDB, and Twitter Bootstrap -- JavaScript
Xymon - Fork of Big Brother -- C
Zabbix - Stores monitoring data in a DB, has agents for almost every OS, can be a virtual appliance -- various lang
Zenoss Core - Supports Nagios plug-in format, based on the Zope application server -- Python

Networking Tools

Hodge-podge of network tools - see also Security Tools and Network Performance Analysis Tools and Orchestration for parallel SSH tools

2ping - Simple bi-directional ping utility, helps determine where packet loss occurs -- Python
aria2 - CLI for downloading HTTP/HTTPS, FTP, SFTP, BitTorrent and Metalink -- C Windows OS X
ARIN WHOIS in JSON - Authoratative (official) info including CIDR and OriginAS, updated every 8h -- collection
arp-scan - Create and send ARP requests -- C
Awesome PCAP - Huge list of tools that work with PCAP captures -- collection
bbcp - Copies files using multiple TCP streams to greatly increase throughput -- C
bbFTP - Uses it's own transfer protocol, optimized for large file transfers -- C
BIRD Internet Routing Daemon (BIRD) - (Almost) fully functional IP routing daemon for Linux, supports tons of standard routing protocols -- C
BPF Tools - BSD Packet Filter (BPF) and pcap toolkit, by CloudFlare -- Python
CERT NetSA Security Suite - Network flow analysis tools -- various lang
Cyberduck - GUI FTP, SFTP, WebDAV, S3 & OpenStack Swift browser for Mac and Windows -- itsaduck
Data Plane Development Kit (DPDK) - Data plane libraries and framework for fast packet processing -- C
dsniff - Great for level 2 analysis or service spoofing -- C
ElastiFlow - Netflow collection and visualization using the ELK stack -- various lang
ExaBGP - The BGP swiss army knife of networking -- Python pip
Fast Data Transfer (FDT) - For writing at disk speed over WANs -- Java
FBOSS (FaceBook Open Switching System) - FB's software stack for managing and controlling their internal switches -- various lang
FreeZTP (Zero Touch Provisioning) - A Zero-Touch Provisioning system built for Cisco IOS -- Python
FRRouting - Replacement for / fork of Quagga with more features -- C
ftptop - Monitor FTP connections in real time -- built-in
Gas Mask - Simple hosts file manager for Mac OS X, switch between host files easily -- Objective C
kcptun - Secure and fast tunnel based on KCP -- Golang
ipcalc - CLI tool to calculate subnets, netmasks, IP ranges, broadcast addresses, and more -- built-in
iptstate - A top-like display of IP Tables state table entries -- built-in
grepcidr - Filter a list of IP addresses against one or more Classless Inter-Domain Routing (CIDR) specifications -- C
GridFTP - Supports parallel streams, optimized for WANs, part of the Globus Toolkit -- C
hosts - Consolidates several reputable hosts files and merges them into a unified hosts file with duplicates removed (ads, malware, gambling, porn, etc) -- collection
hping3 - Create custom TCP/IP packets, very flexible -- built-in
joincap - Alternative to mergecap -- Golang
lftp - Supports many protocols (FTPS, HTTPS, SFTP), scheduling, bandwidth throttling, scripting, and more - feature-rich -- C C++
lldpd - Daemon that can talk LLDP aka the open version of Cisco Discovery Protocol (CDP), handy for network + host mapping -- C
Manito Networks Flow Analyzer - ELK stack netflow analyzer -- Python
moloch - Large scale IPv4 full PCAP capturing, indexing and database system -- JavaScript
mrsync (multicast remote sync) - Transfers from a master to many remote machines using Unix multicast sockets -- C
mTCP - High-performance user-level TCP stack for multicore systems -- C
Multipath TCP Checker - Multipath TCP client tester -- in-browser
My Looking Glass (myLG) - All-in-one CLI network diagnostic tool -- Golang
NAPALM (Network Automation and Programmability Abstraction Layer with Multivendor support) -- Network automation and programmability abstraction layer, for both setting config and config validation -- Python pip
ncat - Improved netcat, written by the Nmap team -- C
Netconf - Web-based GUI for configuring API-less Cisco devices -- Python
netsniff-ng - High performance, zero-copy networking sniffer -- C
netstack - Multi-platform userspace network stack written in Go -- Golang
NETworkManager - All in one network GUI (config, troubleshooting, etc), neat! -- C Sharp
NfSen - GUI for and visualization nfdump -- perl
ngrep - Network grep -- C built-in
Nornir - Python automation framework without a DSL, alternative to managing network devices with Ansible -- Python
nping - Create custom network packets -- C
OpenBGPD - Free implementation of BGP v4 -- C
OpenBMP - BGP Monitoring Protocol collector with real-time monitoring, looking glass, analytics, etc -- various lang
OpenOnload - User-land network stack that requires no modifications to applications to use by intercepting calls -- C
OpenWRT - Full Linux distro for consumer-grade routers, allows for tons of non-vendor customization -- various lang
PFQ - Framework that allows efficient packets capture/transmission, in-kernel functional processing, and packets steering across sockets/end-points -- C
PowerAdmin - Simple Web UI for PowerDNS -- PHP
Quagga - Routing software suite, supports most routing protocols -- C
SiLK (System for Internet-Level Knowledge) - Tool suite supports the efficient collection, storage, and analysis of network flow data, enabling network security analysts to rapidly query large historical traffic data sets -- C
sipcalc - Advanced CLI IP calculator that supports both v4 and v6 -- C
snabb - Worth seeing -- various lang
socat - netcat on steroids, supports serial devices -- C
sslh - Protocol multiplexer, let multiple daemons listen on a single port -- C
tcpflow - TCP demultiplexer, each flow is stored in it's own file -- C++
tcpreplay - Capture, edit, and replay network traffic -- C
tracepath - Traceroute that doesn't require root -- C
tracetcp - Traceroute via SYN packets -- C++
Trigger - Network automation toolkit written in Python, created by AOL -- Python
UDR - UDT wrapper for rsync that improves throughput of large data transfers over long distances -- C++
vFlow - High-performance, scalable and reliable enterprise netflow collector with Kafka integration, by Verizon -- Golang
webterm appliance - Debian-based networking toolbox, runs in a Docker container + Firefox, by the GNS3 team -- neat
WireShark - The classic network analyzer -- C
WireShark Tools - Superb list of network tools from the WireShark wiki -- collection
Zenmap - Official GUI for Nmap -- C Windows OS X

Network Performance Analysis Tools

Load generation, benchmarking, profiling, and latency simulation tools for TCP/IP networks - see also Web and HTTP Performance Analysis Tools and Performance Analysis Tools

ARGUS (Audit Record Generation and Utilization System) - Generates network activity reports -- C
Augmented Traffic Control (ATC) - A tool to simulate network conditions, by Facebook -- Python
bmon - Console based network monitor -- C
clumsy - Simulate poor network conditions on Windows -- C Windows
Comcast - Simulate crappy network connections -- Golang OS X
dummynet - Simulates/enforces queue and bandwidth limitations, delays, packet losses, and multipath effects -- C Windows
ESnet Fasterdata Knowledge Base - Provides proven, operationally sound methods for troubleshooting and solving performance issues -- collection hpcwisdom
EtherApe - Graphical network monitor, pretty output -- various lang
Flent - Python wrapper to run mutliple netperf/iperf3/ping in parallel, formerly netperf-wrapper -- Python
Flowgrind - Distributed TCP traffic generator -- C
iftop - top for network interfaces -- C
intrace - Enumerate IP hops using existing TCP connections -- C
iperf3 - Supports tuning of various parameters related to timing, protocols, and buffers -- C
iptraf-ng - Updated fork of iptraf -- C
jnettop - Terminal / ncurses traffic visualizer -- C
mtr (my traceroute) - Combines ping and traceroute into a single program -- C
Muxy - Muck with your system and application context layers 4-7 -- Golang OS X
namebench - Hunts down the fastest DNS servers for your computer to use -- Python Windows OS X
netatop - Kernel module for atop to watch and report on network packets -- C
netem - Network emulator for testing variable delay, loss, duplication and re-ordering -- C
NetHogs - Displays per-process bandwidth usage -- C C++
Network Link Conditioner - Simulate bandwidth, latency, and packet loss, by Apple -- closed source OS X
nfdump - Captures network flows including sFlow, NetFlow, NetFlow v9, ipfix, etc -- perl
nicstat - vmstat for network interfaces -- C
nload - Console application that monitors network traffic and bandwidth usage in real time, neat ASCII graphs -- C++
ntopng / ntop-ng - New version of the popular ntop tool -- C
netperf - Network load generator, by HP -- C
Paris Traceroute - Shows proper network topology when load balancers and load-balanced routers are used -- C
Ruru - Real-time TCP latency monitoring, utilises Intel DPDK for high speed packet processing with a Node.JS frontend for visualizing the data -- various lang
SmokePing - Network latency visualizer, written by the MRTG and RRDtool guy -- perl
ss - Socket statistics, a modern netstat -- built-in
Stanford Linear Accelerator Center - Network Monitoring Tools - MASSIVE list of network monitoring tools -- collection
tc - Built-in Linux kernel traffic control -- built-in
TCP Throughput Calculator - See name -- in-browser
tcpdive - TCP performance analysis tool, implemented as SystemTap scripts -- C
tcptrack - Console based connection tracker -- built-in
Tracebox - Detect middleboxes (NAT, transparent proxies, etc) in a network path -- C++
trickle - Userspace bandwidth shaper -- built-in
vnStat - Console based traffic monitor, supports statistic collecting -- C
WinMTR - Windows GUI for MTR -- C++
Yconalyzer - Monitor and analyze TCP connections -- C++

Orchestration

OS and VM level orchestration as well as parallel SSH tools - see also Containers and Distributed Systems Tools for container orchestration and Terminal Tools and SSH Clients for SSH clients and SSH Tools for misc SSH tools and Provisioning Tools

Ansible - CM and orchestration, also can do provisioning -- Python
Archipel - Use XMPP push notifications to manage, supervise, and orchestrate VMs -- Objective-J
Batou - Define and perform automated service deployments -- Python pip
Capistrano - Use Ruby to run scripts/commands and push software via SSH, uses a Rake DSL -- Ruby gem
ClusterSHISH - Cluster SSH for Windows, works with PuTTY and OpenSSH for Windows -- closed source Windows
ClusterSSH - Make a change on many servers at the same time -- perl
csshX - Cluster SSH for OS X -- C
KeyBox - Web-based SSH console that executes commands on multiple shells simultaneously and supports terminal sharing -- Java
KeyBox-OpenShift - KeyBox for OpenShift gears -- Java
ManageIQ - Upstream OSS project for Red Hat's CloudForms -- Ruby
Mass Parallel SSH (mpssh) - Simple parallel SSH -- C
mcollective (Marionette Collective) - Orchestration, can be used independently of Puppet -- Ruby gem
mussh - MUltihost SSH -- C built-in
OpenLMI (Open Linux Management Infrastructure) - Manage, monitor, and configure servers via API calls (instead of SSH), included in RHEL 7 -- various lang
orgalorg - Next generation parallel SSH tool because most other major ones are no longer maintined -- Golang
parallel - Execute jobs in parallel using one or more computers -- built-in
parallel-ssh (pssh) - Parallel version of OpenSSH tools - comes with prsync, pscp, pnuke, and pslurp too -- Python built-in
Parallel Distributed Shell (pdsh) - Kick off many SSH sessions in parallel -- C
PyDSH - Python Distributed Shell, parallel SSH -- Python
Rex - Framework for server orchestration and to simplify system administration -- perl
Rubber - Capistrano/rails plugin that makes it easy to deploy/manage/scale to various service providers -- Ruby
Rundeck - Job scheduler and runbook automation, enable self-service access to existing scripts and tools -- Groovy
Salt / Saltstack - Orchestration, server provisioning, and configuration management -- Python
Spacewalk - Remote commands/orchestration, patch management, and more - the upstream for Red Hat Satellite 5.x and earlier -- various lang
Teleport - Front-end for teams, includes session capture and replay, auditing, 2FA, session sharing, and more -- Golang
tmux-cssh - Cluster SSH via tmux -- shell
xCAT (Extreme Cloud Administration Toolkit) - Complete all in one management solution (provisioning, orchestration, management, etc) supports almost every UNIX and next generation platform, by IBM -- legit

Package Patch and Repository Tools

Repos, RPM/APT packages, packaging guidelines, patching, and patch management - see also Provisioning Tools

apt-dater - Simple ncurses frontend for package management via SSH, also supports yum -- C
aptly - Swiss army knife for Debian repository management, has the ability to take snapshots for easy rollback -- C
AutoPkg - Packaging and distribution for OS X, great for managing many laptops -- Python OS X
CentOS Errata for Spacewalk (CEFS) - Import errata information from CentOS-announce into Spacewalk -- useit
CentOS Repositories - Large list of both official and unofficial CentOS software repositories -- collection
CentOS Software Collections (SCL) - Use multiple versions of software on a system without disturbing the system default version -- C
Copr - Automatic build system providing a package repository as its output, by Fedora -- C
cowbuilder - Package builder that uses copy-on-write (COW) to speed up the build process -- C
DNF aka Dandified yum - yum v4 packaging system, added to upcoming Fedora/RHEL/CentOS 8 releases -- article
ELRepo - Repo that focuses on hardware related packages, supports RHEL and CentOS -- repo
Extra Packages for Enterprise Linux (EPEL) - Supports CentOS, RHEL, Scientific Linux, and Oracle Linux -- repo
Extra Packaging Guidelines and Policies for EPEL - Packaging guidelines, great even if not creating EPEL stuff -- readit
Fedora Packaging Guidelines - Excellent information that can be applied to CentOS & RHEL -- readit
Flatpak - Standalone, sandboxed apps so you can avoid package management all together -- C
fpm (Fucking Package Management) - Build packages for multiple platforms (deb, rpm, etc) with great ease and sanity -- Ruby gem
fpm-cookery - Tool for building software packages with FPM -- Ruby gem
Habitat - Creates platform-independent build artifacts and provides built-in deployment and management capabilities -- Golang
Homebrew (aka brew) - Tons of packages for Mac -- Ruby OS X
Koji - Software that builds packages for Fedora, can be used for other stuff too, uses mock -- C
Mock - Build packages in a simple chroot so you don't blow up your system -- C
mrepo - RPM repository management tool supporting ftp/http/sftp/rsync/rhn/you, formerly Yam -- Python
Munki - Managed software installation for OS X, great for managing laptops -- Python OS X
OStree - Tool for managing bootable, immutable, versioned filesystem trees (not really a package manager but...) -- thefuture C
pkgr - Made deb or RPM packages out of any Ruby, NodeJS, or Go app -- Ruby
Pulp - Next generation repository management, a component of Red Hat Satellite 6 -- Python
Red Hat Software Collections (SCL) - Use multiple versions of software on a system without disturbing the system default version, use this to get the newest / latest versions of things -- repo
reposync - Synchronize yum repositories to a local directory -- built-in
rpm-ostree - Hybrid image/package system with atomic upgrades and package layering -- C thefuture
RPM Fusion - Provides software that the Fedora Project or Red Hat doesn't ship -- repo
schroot - Allow non-root users to create chroot environments, great for package testing -- built-in
Spacewalk - Patch management, remote commands, and more - the upstream for Red Hat Satellite -- various lang
Tito - Tool for managing RPM based projects using git for their source code repository -- Python
yum-presto - yum plugin that provides support for downloading package deltas -- article
yum-security - Plugin to only install security updates -- built-in

Performance Analysis Tools

Non-specific and all-in-one performance monitoring tools - see also web, network, storage, and RDBMS and Tracing and Profiling

atop - Supports both real-time and historical performance monitoring -- C
bwm-ng - Small and simple console-based live network and disk I/O bandwidth monitor for a wide variety of UNIXes and Windows -- C
Conky - Lightweight system monitor for X windows -- C++
dstat - Versatile replacement for vmstat, iostat, netstat and ifstat -- Python
Glances - Real-time performance monitoring, written in curses and Python -- Python
hazelnut - Python lib to parse /proc/meminfo -- Python pip
htop - top replacement, has a few additional features -- C
Linux Performance Observability Tools - Awesome graphic that shows you which tool to use, by Brendan Gregg -- yells at drives
mem_logger.sh - Monitor a processes' memory usage over time -- shell
Munin - Historical performance monitoring to help determine when you server became "slow" -- perl
NetData - Real time performance visualization and dashboards -- C
nmon - Provides both real-time and historical performance metrics -- C
NumaTOP - top for NUMA systems, shows hotspots, call chains, etc -- C
PerfKit Benchmarker - Open effort to define a canonical set of benchmarks to measure and compare cloud offerings (disk, network, CPU, etc) -- various lang
Performance Co-Pilot (PCP) - System performance and analysis framework, included in RHEL 7 -- C
Phoronix Test Suite - Benchmarking and profiling suite, very feature-rich and versatile -- PHP
pidstat - vmstat type output for CPU, disk I/O, page faults, and more on a per-process basis -- built-in
pmap - Shell scripts for tracking memory usage using "pmap" -- shell
PowerTOP - Real-time power consumption on a per-process & per-thread basis, by Intel -- C++
ps_mem - Accurately reports core memory usage for a process -- Python
ptop - top/ntop-like task monitor written in Python -- Python pip
recap - Collects info from various standard utilities (free, sar, vmstat, etc) at specified intervals, by Rackspace -- various lang
saidar - ncurses based program for viewing system statistics -- built-in
slabtop - Tutorial on how to use slabtop, useful when you have no idea on how your RAM is being used -- article
smem - Reports memory usage based on proportional set size (PSS) instead of the usual resident set size (RSS) -- C
sysdig - Linux system exploration and troubleshooting tool with first class support for containers -- C++
USE Method - Brendan Gregg's rosetta stone for performance analysis and tuning -- article
VMtouch - File system cache diagnostics and control -- C

Provisioning Tools

OS provisioning, image creation, installation, bootstrapping, and lifecycle management - see also Package Patch and Repository Tools and Containers and Distributed Systems Tools and Live CD Tools

Atlantis - A unified workflow for collaborating on Terraform through GitHub and GitLab, by Hootsuite -- Golang
Bento - Baseboxes provided by Chef, for Packer + Vagrant -- various lang
bootrino - Provision run-in-RAM / diskless OSes (Linux, etc) in various clouds -- various lang
Box-Cutter - Hashicorp's community repo for Packer & Vagrant templates -- Ruby
Clonezilla - Disk image/cloning tool, supports most file system types -- perl shell
cloud-init - Configures settings the first time a system spins up (SSH keys, hostname, variables, etc), note NoCloud -- C
Cobbler - Provisioning system used in Red Hat's Satellite -- Python
Crowbar - Multi-purpose provisioning tool, created by Dell -- Ruby
Fog - Computer / OS cloning tool, also has remote client management capabilities -- C++
Foreman - Provisioning and life cycle management -- Ruby Windows OS X
iPXE - GPL'ed version of PXE, official replacement for gPXE -- C
Katello - Candlepin + Pulp + Foreman, the core of Red Hat Satellite 6 -- various lang
Kickstart - The classic Red Hat tool -- various lang
kitchen-terraform - Test Kitchen plugins for testing Terraform configurations with InSpec -- Ruby gem
Metal as a Service (MaaS) - Ubuntu provisioning system -- various lang
netboot.xyz - Simple iPXE menu and installer -- shell
Overcast - VM orchestration and provisioning for DigitalOcean, Linode and Amazon, or locally using Vagrant + Virtualbox -- various lang
Packer - Automates VM creation for multiple platforms (VMware, AWS, etc) -- Golang
Terraform - Infrastructure provisioning using existing tools, supports many providers (AWS, Azure, DO, OpenStack, etc) -- Golang Hashicorp
Terraformer - Generate terraform files from existing infrastructure (reverse Terraform), supports AWS and GCP, by Google -- Golang
Terraform Landscape - Makes terraform plan easier to read -- Ruby
Terragrunt - Tools for keeping your Terraform configurations DRY, working with multiple Terraform modules, and managing remote state -- Golang
Terraparty - GUI Terraform script creator -- in-browser
Terratest - Makes it easier to write automated tests for your infrastructure code, provides a variety of helper functions and patterns for common infrastructure testing tasks -- Golang
tflint - Terraform linter for detecting errors that can not be detected by terraform plan -- Golang
Vagrant - Quickly spin up environments for local testing and development -- Ruby
Vagrant Plugins - A list of Vagrant plugins on the official Hashicorp wiki -- collection
Vagrant Manager - GUI to manage Vagrant boxes -- Windows OS X
vagrant-cachier - Cache BLOB downloads to reduce network usage -- Ruby
vagrant-host-shell - Simple plugin to run commands on the VM when it boots (think cloud-init) -- Ruby
vagrant-hostsupdater - Plugin to add your own /etc/hosts to the VM -- Ruby
vagrant-lxc - Provision to Linux containers instead of the usual VirtualBox -- Ruby
vagrant-triggers - Run arbitrary scripts on the guest before and/or after Vagrant commands -- Ruby
vagrant-vbguest - Auto-install the latest VirtualBox tools at boot time (if necessary) -- Ruby
veewee - Easily (and repeatedly) build custom Vagrant base boxes, KVMs, and VM images -- Ruby
veewee-to-packer - translate veewee templates to Packer templates -- Ruby gem
Salt / Saltstack - Orchestration, server provisioning, and configuration management -- Python

Python Tools and Resources

Python stuff of note

argparse - Parser for command-line options, arguments and sub-commands -- Python
atexit - Exit handlers -- Python
Awesome Python - Very large list of Python resources -- collection
bpython - Killer interface for the Python interpreter -- Python
Celery - Async task/job queue based on distributed message passing -- Python
ciscoconfparse - Parse, audit, query, build, and modify Cisco IOS-style configurations -- Python pip
Collections - High-performance container data types -- Python
Common Python Mistakes - Link and discussion on HN -- article
Easy-Python - Collection of Python resources that "you didn't know you would need" -- collection
exscript - Write less code using than either pure paramiko or netmiko -- Python
Fabric - Uses paramiko to implement a higher-level API for performing commands over SSH, particularly for deployment sysadmin tasks -- Python pip
Faker - Generate fake data easily -- Python pip
Fire - Turn any Python module, class, object, function, etc into a CLI -- Python
functools - Higher-order functions and operations on callable objects -- Python
FunkLoad - Functional and load web tester -- Python pip
getpass - Enter a password without echoing what they type to the console -- Python
Google Python Style Guide - Google's Python style guide -- article
inspect - Inspect live objects -- Python
IPython - Interactive Python shell and the kernel for Jupyter -- Python
Itertools - Functions creating iterators for efficient looping, iterator building blocks -- Python
Jinja2 - Templating language for Python -- Python pip
Jupyter - The language-agnostic parts of IPython -- Python
Logging - Flexible event logging system for applications and libraries for all modules and more -- Python
Mailer - The best e-mail module -- Python
more-itertools - More routines for operating on iterables, beyond itertools -- Python pip
netaddr - A network address manipulation library for Python -- Python
netmiko - Multi-vendor library to simplify Paramiko SSH connections to network devices -- Python
netminko_tools - Command line tools built on Netmiko to simplify information gathering -- Python
os - Interact with the OS -- Python
paramiko - SSH2 protocol library for Python, provides both client and server -- Python pip
pdb - Python debugger -- Python
pexpect - Expect-like module -- Python
pycsco - Python modules to simplify the use of working with Cisco Nexus switches -- Python
PyEnv - Simple Python version management that keeps everything within your home directory, virtualenv alternative -- shell
Pynag - Interface with Nagios via Python -- Python pip
PyPI (Python Package Index) - Software repo for Python packages, like Ruby gems or a RPM repo -- collection
Python Reference - A collection of useful scripts, tutorials, and other Python-related things -- collection
PyPy - Python alternative with advance features (JIT compiles, sandboxing, etc) -- Python
python-patterns - A collection of design patterns and idioms in Python -- collection
python-prompt-toolkit - Library for building interactive command lines -- Python pip
Python Patterns - Python patterns by Brandon Rhodes -- collection
RadSSH - Paramiko-based parallel SSH -- Python pip
Requests - The best HTTP library -- Python pip
scapy - Interactive packet manipulation for Python -- Python pip
selenium - Browser automation -- Python
sh - Library that allows you to call any program (shell command) as if it were a function -- Python pip
Subprocess - Spawn subprocesse and collect their output -- Python
sys - System-specific parameters and functions -- Python
TCPWatch - TCP monitoring and logging tool -- Python pip
tempfile - Generate temporary files and directories -- Python
TextFSM - Create a pool of templates to parse text, then use TextFSM to parse useful information from a variety of sources -- Python
urllib - Open, read, parse URLs and robots.txt -- Python
virtualenv - Tool to create isolated Python environments -- Python pip
virtualenvwrapper - Extensions to virtualenv -- Python pip
wtfpython - A collection of surprising Python snippets and lesser-known features -- collection
xlwings - Replace your Excel VBA code with Python -- Python pip

Python Programming Tutorials

Tutorials, exercises, and challenges for learning Python. I have no idea how good/bad these are

500 Lines - Many full Python programs written in 500 lines or less, great for beginners
CheckiO - Challenges, shows all submitted solutions to a challenge and people vote for best - great way to see each POV -- in-browser
Codecademy - Codecademy's online Python course
CodingBat - Practice problems
Coursera - Online Python courses at various institutions
Dive Into Python 3 - Free ebook
edX - Python courses at edX
Google Python Class - By the GOOG
importpython's Python Book List - Includes both free and pay, ebooks and physical
Intermediate Python - Free ebook
Invent with Python - Series of free ebooks, includes Automate the Boring Stuff with Python, recommended books
Learn Python, Break Python - Free ebook
MIT Open Courseware - Introduction to Computer Science and Programming - Focuses on Python
MIT Open Courseware - A Gentle Introduction to Programming Using Python - Final project is a Tetris game in Python
MIT Open Courseware - Objects in Python - Python tuples, lists, and dictionaries, as well as the concept of mutability and how to avoid problems relating to it.
MIT Open Courseware - Python Tutorial - Python tutorial for people familiar with basic programming concepts
New Coder - Python exercises
Online Python Tutor - 100% in-browser
Programming Praxis - Programming exercises, many posted solutions are in Python
Python Challenge - A riddle in Python
Python for Infomatcis - Free ebook
Python for You and Me - The 2.x version is linked on the main page
Python Practice Projects - Several practice exercises
Python 2.x Tutorial - For 2.x, part of the official documentation
Python 3.x Tutorial - From the official documentation
Quiz and Learn Python - Designed for mobile devices
r/dailyprogrammer - Programming exercises, includes Python
r/learnpython - Subreddit for beginners, be sure to check the wiki too
Supporting Python 3 - Free ebook that focuses on porting to Python 3.x
Think Python: How to Think Like a Computer Scientist - Awesome free ebook
Tutorials Point's Python Tutorial - Another one!

RDBMS and SQL Tools

Tools for interacting with and related to the major DBs and SQL

Adminer - GUI for database management in a single PHP, formerally phpMyAdmin -- PHP
CockroachDB - Open source version of Google's Spanner storage system -- thefuture Golang
DBeaver - OSS multi-platform GUI that supports almost every DB, built from Eclipse -- Eclipse
DB Browser for SQLite - GUI database browser for SQLite instances -- C++
Flyway - Version control for DB schemas, supports most DBs -- Java
gh-ost - Online schema migrations for MySQL, by GitHub -- Golang
HeidiSQL - GUI SQL DB browser and editor -- Windows OS X
Large Hardon Migrator (LHM) - Live, online MySQL migrations -- Ruby
Liquibase - Tracking, managing, and applying database schema changes, SVN for DBs -- Java
MaxScale - General purpose DB query proxy, router, and load balancer by MariaDB -- C
mycli - CLI for MySQL and derivates with auto-completion and syntax highlighting -- Python
mydumper (MySQL Data Dumper) - Much better than mysqldump, works in parallel -- perl
MyRocks - RocksDB with a MySQL front-end / interface -- C++
MySQL sys schema - Collection of views, functions and procedures to help MySQL administrators get insight into MySQL usage -- SQL
MySQL Utilities - Official collection of MySQL tools -- various lang Python
MySQL Workbench - The official MySQL GUI for admins, devs, DBAs, and architects -- various lang
Oracle TPT Scripts - Tab completion for Oracle -- SQL
orchestrator - MySQL replication topology management and visualization tool, GUI -- Golang
Peloton - Self tuning, self optimizing DB -- C++
Percona Toolkit for MySQL - Percona's special toolkit -- various lang
pgcli - Postgres CLI with autocomplete and syntax highlighting -- Python
pgloader - Fast data loader for PostgreSQL -- Lisp
pgweb - Web-based PostgreSQL DB browser -- Golang
pg_repack - Remove bloat from tables and indexes without using an exclusive lock -- C
Phinx - Database migrations in SQL or PHP -- PHP
Postgres-XL - Scale-out version of PostgresSQL -- C
Postgres.app - All-in-one version of Postgres for local testing on a laptop -- C
PostgREST - Create a REST API for any Postgres DB -- Haskell
PostgreSQL GUI Tools - A huge list on the official wiki -- collection
Presto - Distributed SQL query engine for big data, by Facebook -- Java
rdbms-subsetter - Generate a random sample of rows from a relational database that preserves referential integrity, great for using production data for testing/dev -- Python
rlwrap - Add history and tab completion to SQLplus -- C
SchemaSpy - Analyze the metadata of a schema and visualize it in HTML -- Java
Sequel Pro - MySQL management GUI for Mac -- OS X
shift - Schema migrations for MySQL, by Square -- Ruby
SQLite - Self-contained, serverless, zero-configuration, transactional SQL database engine, great for testing -- C
sqlmap - Detect and exploit SQL injection flaws, pen testing tool -- Python
SQL Fiddle - Write and test SQL -- in-browser
wal-e - Simple continuous archiving for PostgreSQL -- Python
WebScaleSQL - Huge scale MySQL with contributions from Facebook, Google, LinkedIn, and Twitter -- C C++
WWW SQL Designer - Designing RDBMS schemas features saving, exporting to XML, and SQL script creation, free SaaS version here -- JavaScript

RDBMS Performance Analysis Tools

Load generation, benchmarking, telemetry, and profiling for various RDBMS platforms - see also Storage Performance Analysis Tools and Performance Analysis Tools and Tracing and Profiling and Network Performance Analysis Tools and Metrics and Time Series Data

Anemometer - MySQL slow query log monitor and analyzer, by Box -- PHP JavaScript
HammerDB - Load testing and benchmark tool, supports most DBs -- Tcl
innotop - "top" for MySQL -- NOTE: beware of exposing your password -- perl
MySQLtuner-perl - Analyzes a MySQL installation and provides suggestions to increase performance -- perl
MySQL Performance Analyzer - Open sourced by Yahoo -- Java
MySQL Performance Tuning Cheat Sheet - Superb Reddit post on performance evaluation and tuning -- article
MySQL Performance Tuning Checklist - No bullshit list in about 15 bullet points -- collection
mytop - Another "top" for MySQL -- perl
Open PostgreSQL Monitoring (OPM) - Includes a web console, nice GUI -- JavaScript
Percona Monitoring Plugins - Some of the best mySQL plugins -- various lang
Percona Toolkit for MySQL - Percona's internal tools -- various lang
pg_activity - htop for PostgreSQL -- Python
pg_view - PostgreSQL monitoring, supports ncurses, console, and JSON output -- Python pip
pgBadger - PostgreSQL log analyzer -- perl
PgHero - A performance dashboard for Postgres - health checks, suggested indexes, and more -- JavaScript
PGObserver - Killer PostgreSQL monitor, includes dashboard -- Python
Silly Little Oracle Benchmark 2 (SLOB2) - Stresses and benchmarks Oracle DBs, works at the RDBMS layer -- various lang
Swingbench - Oracle load generator -- closed source
SysBench - Evaluates OS parameters that are important for DBs, does not require a DB to be installed -- C
Tsung - Distributed stress tester, also supports stress testing DBs -- Erlang

Regular Expressions

regex checkers, creators, evaluators, debuggers, and tutorials - see also Shell Scripting and Tools and Software Development Tools

Debuggex - Online regex debugger -- in-browser
perlretut - perl-focused but very useful for all regex -- article
Refiddle - Online, supports JavaScript, Ruby, and .NET only -- in-browser
regex101 - Online regex tester and debugger, supports multiple languages -- in-browser
RegexOne - Learn regular expressions with simple, interactive examples -- tutorial
regexper - Regex visualizer using railroad diagrams, great for debugging -- in-browser
RegExr - Another online regex tool that includes cheat sheets, examples, and community-contributed expressions -- collection
RegularExpressions.info - THE BEST regex site -- collection
Regular Expressions - A Gentle User Guide and Tutorial - The easy way -- tutorial
RexV.2 - Online Regex evaluator, supports multiple languages -- in-browser
Rubular - Online Ruby-only regex evaluator -- in-browser
txt2re - Regex generator, recommended -- in-browser
txt2regex - Converts human sentences to regex, written in bash -- shell

Ruby Tools and Resources

Ruby toolbox full of junk

Awesome Ruby - A collection of awesome Ruby libraries, tools, frameworks and software -- collection
Bundler - Manage Gem dependencies using simple config files -- Ruby gem
did_you_mean - Suggestions for typos in Ruby code -- Ruby
fog - Library for communicating with clouds -- Ruby gem
Omniref - A better search site for Ruby documentation -- collection
Pry - IRB alternative, very feature-rich, great for debugging -- Ruby gem
Rake - Make / Makefile-like build utility -- Ruby gem
rbenv - Alternative to RVM -- shell
replicate - Dump and load relational objects between Ruby environments (eg: prod and dev) -- Ruby gem
RSpec - Behavior-driven development (BDD) testing framework -- Ruby
RuboCop - Static code analyzer that enforces guidelines -- Ruby gem
Ruby Gems - The Ruby package manager, gems are essentially libraries -- Ruby gems
Ruby Toolbox - Trillions of Ruby projects, categorized -- collection
RVM (Ruby Version Manager) - Install, manage, and work with multiple Ruby environments -- Ruby

Ruby Programming Tutorials

Tutorials, exercises, and challenges for learning Ruby. I have no idea how good/bad these are

Basic Ruby - Videos and exercises
Codecademy - Ruby course at Codecademy
Coderbyte - Programming challenges
Codewars - More challenges!
Coursera - Online Ruby courses at various institutions
edX - Ruby courses at edX
exercism.io - Challenges with peer review!
Introduction to Programming with Ruby - By Tealeaf Academy & Launch School
Learn Ruby the Hard Way - Have fun with this
r/dailyprogrammer - Programming exercises, includes Ruby
r/learnruby - Subreddit for beginners
Rubeque - Super easy to hard level challenges
Ruby Koans - The most highly recommended tutorial
Ruby Monk - Free, interactive tutorials to help you discover Ruby idioms in your browser
Ruby Quiz - Weekly programming challenge
Ruby Warrior - Coding challenges WARNING sound, but you can turn it off
Treehouse Ruby Courses - Recommended
Try Ruby - Interactive tutorial in your web browser
Tutorials Point - Interactive online course

Secrets Management

Password, private key, and API key storage and management tools - see also Security Tools and SSL Tools and Two Factor Authentication and VPNs and Tunnels

Bitwarden - The new hotness in password management -- various lang
blackbox - Safely store secrets in Git, by Stack Exchange -- shell
Diceware - Neat IRL passphrase generator -- doitirl
credstash - Secrets management using AWS KMS -- Python pip
GPG (GNU Privacy Guard) - The original! Store em in text files and encrypt -- C pro
GRC Password Generator - Generates 63 bit passwords -- in-browser
Kee - Auto-fill website logins using KeePass as a source, like LastPass -- C# Firefox
Keybase - Upload your public key and find other people's public key via their social media user name(s) -- in-browser
KeePass - Lightweight, easy to use, GUI password manager, runs on most platforms -- C# Windows
Keepass2Android - Compatible with KeePass 2.x -- Android
KeePassDroid - Open source version of KeePass 1.x for Android -- Android
KeePassXC - Supports YubiKey and TOTP, forked becasue KeePassX is no longer being updated -- C++
KeeWeb - Cross-platform password manager compatible with KeePass -- JavaScript
Keywhiz - A system for distributing and managing secrets (API keys, certificates, etc), by Square -- Java
kpcli - Command line interface / CLI for KeePass -- perl
lastpass-cli - CLI for LastPass -- C
MacPass - A free, open-source, KeePass-compatible password manager for macOS -- Objective-C
msktutil - Keytab client for a Microsoft Active Directory environment -- built-in
One-Time Secret - Create links that self-destruct after a single viewing, great for sharing passwords -- Ruby
pass (passwordstore) - Uses GPG at it's core, supports tracking password changes in git -- shell
passff - Addon for interacting with the a pass aka passwordstore repository -- Firefox
Password Pusher - Links to passwords expire after a certain number of views and/or time has passed, RoR app -- Ruby
Password Safe - Designed by Bruce Schneier himself -- bam
pwd.sh - Script to manage passwords in an encrypted file using GPG -- shell
pwgen - Password generated, included in most Linux distros -- built-in
Secrets OPerationS (SOPS) - Secrets management, by Mozilla -- Python
Sneaker - Store secrets on S3 using Amazon KMS -- Golang
TeamPass - Collaborative password management using the LAMP stack -- PHP
Vault - Tool for storing secrets (API keys, passwords, certs, etc) by Hashicorp -- Golang
vault-ui - React UI for Hashicorp Vault -- JavaScript
xca - OSS all in one PKI -- C++
zxcvbn - Password strength estimator, written by Dropbox, operates in a browser window -- CoffeeScript in-browser

Security Tools

Misc security tools - see also Live CD Tools and Networking Tools and Secrets Management and SSL Tools and Two Factor Authentication and VPNs and Tunnels and Logging

Advanced IP Scanner - For Windows, recommended -- closed source
afl-fuzz (American Fuzzy Lop) - One of the best fuzzers -- C
AIDE (Advanced Intrusion Detection Environment) - File integrity checker, alternative to Tripwire -- various lang
Amass - Automatically obtains subdomain names in a variety of ways and uses that info to build maps of the target network, by OWASP -- Golang
Angry IP Scanner - GUI network scanner, supports plugins, -- Java Windows OS X
Armitage - GUI for Metasploit -- Java
ATA Secure Erase - Send a signal to an ATA drive to perform a hardware-based erase, the ONLY way to wipe a SSD properly -- article
Attack Surface Analyzer 2.0 - See exactly what changed post-OS install or post-software install, by Microsoft -- Windows
auditd-attack - A Linux Auditd rule set mapped to MITRE's Attack Framework -- collection
authconv - Web app authorization coverage scanning -- JavaScript
Awesome Honeypots - Curated collection of honepots and honeypot resources -- collection
bettercap - Swiss Army knife for 802.11, BlueTooth, and Ethernet networks reconnaissance and attacks -- Golang
Brida - Bridge between Burp Suite & Frida, lets you use and manipulate applications own methods while tampering the traffic exchanged between the applications and their back-end services/servers -- various lang
bro - Framework for network analysis and security monitoring -- C++
CALDERA - Automated adversary emulation system that performs post-compromise adversarial behavior within Windows Enterprise networks -- Python
cherrytree - Hierarchical note taking application, excellent for red team / pentest notes -- Python
chkrootkit - Rootkit checker, best used from a live CD -- C
CIS Linux Benchmarks - Linux OS hardening guides, superb! -- collection
Common Vulnerability Scoring System Calculator - Version three -- collection
ConfigServer Security and Firewall (CSF) - Stateful Packet Inspection (SPI) firewall, Login/Intrusion Detection and Security application for Linux servers -- various lang
CSP Evaluator - Check if a Content Security Policy (CSP) serves as a strong mitigation against cross-site scripting attacks, by Google -- in-browser
cuckoo - Feed in malware URL, it fires up VM, and provides a report about the actions the malware took -- in-browser
CyberChef - A web app for encryption, encoding, compression and data analysis -- in-browser JavaScript
Cyber Security Transformation Chef - CyberChef as a Burp Suite extension -- Java
dcfldd - Enhanced dd with security and forensics features -- C
Dradis CE (Community Edition) - Reporting framework for generating one-click reports (vuln scanning, pentest, etc) -- Ruby
Dshell - Network forensic analysis framework, written by the US Army -- Python
EncFS - Encrypted file system in user space via FUSE -- C++
fail2ban - Watches log files to ban IPs based on rules (too many failed logins, exploit attempts, brute force attacks, etc) -- Python
Forensics Acquisition of Websites (FAW) - Download and save social media sites, paid version has more features -- closed source Windows
Forensics Wiki - Digital forensics wiki, tons of tools and information -- wiki
FTimes - System baselining and evidence collection tool -- C
fwknop (FireWall KNock OPerator) - Single Packet Authorization (SPA), authoriation packet from you opens firewall rules so only you can get in -- various lang
Google Safe Browsing Site Status - Use Google for site/URL malware analysis -- in-browser
GRR Rapid Response - Live forensics for incident response via a Python agent, dump memory, isolate host, snoop syscalls etc -- Python
hashcat - World's fastest CPU password cracker / password recovery -- C
Hybrid Analysis - Dree malware analysis service that detects and analyzes unknown threats using a unique Hybrid Analysis -- in-browser
icebreaker - Automates internal network attacks against Active Directory to deliver you plaintext credentials -- various lang
Information Security Cheat Sheets and Checklists - An assortment of IS checklists and cheat sheets, -- collection
Jenkins Pentesting - Title, please contribute -- various lang
Just the Basics (JTB) Investigator - Simple menu & CLI to automate repetitive everyday tasks -- Python
geoiplookup - Uses the GeoIP DB and library to determine which physical country an IP or host originates in, includes PAM library -- built-in
Hindsight - Internet history forensics for Google Chrome/Chromium -- Python
Jailkit - chroot toolkit -- C
Joe's Sandbox (Cloud Basic) - Deep automated malware analysis -- in-browser
Kali NetHunter Linux Root Toolkit (LRT) - Collection of bash scripts that setup and install Kali Linux NetHunter from a Linux/OSX environment onto a NetHunter supported device -- shell
LinEnum - Enumerate a local Linux environment -- shell
Lynis - Auditing and hardening tool, supports most Unix-like operating systems -- shell
Malcom - Easily deployable network analysis tool suite for full packet capture artifacts (PCAP files) and Zeek logs -- various lang
Massscan - Scans in parallel and async for the fastest scans around -- C
Metasploit - Classic exploit framework -- various lang
National Checklist Program - U.S. government repository of publicly available security checklists (or benchmarks) that provide detailed low level guidance on setting the security configuration of operating systems and applications -- collection
National Software Reference Library (NSRL) - Large collection of diskprints from various software and malware -- collection
National Vulnerability Database - Gotta catch em all -- collection
Nikto2 - Web & app server vulnerability scanner -- perl
nmap - Classic port scanner -- various lang
nmap_vulners - Emumerate and list vulnerabilities during an nmap scan similar to Nessus -- collection
nmap Scripting Engine (NSE) - Tons of scripts for nmap -- various lang
oclHashcat - World's fastest CPU + GPU password cracker / recovery software -- C
OpenSCAP - NIST Certified SCAP 1.2 toolkit -- C
OpenVAS - Vulnerability scanner, forked from the now closed-source Nessus scanner -- C
Open Web Application Security Project (OWASP) - Focus on web application security -- organization
Oracle Database Attacking Tool (ODAT) - Open source penetration testing tool that tests the security of Oracle databases remotely -- Python
OS X Auditor - Forensics tool for Mac -- OS X JavaScript
OSSEC - Host based intrusion detection system (HIDS), supports most Unix-like OSes -- C Windows OS X
OWASP Cheat Sheet Series - Contains all OWASP cheat sheets, new v2 -- collection
PALADIN - Easy to use Linux-based live CD for forensic analysis -- various lang
pfsense - The best firewall software, supports appliances and live CDs -- C
preeny - Some helpful preload libraries for pwning stuff -- C
Prey - Open source anti-theft software for almost all platforms -- shell Java mobile
ProcDOT - All in one visual malware analysis and visualization, by CERN -- closed source various lang
Purple Team ATT&CK Automation - Metasploit automation of MITRE ATT&CK TTPs -- Ruby
Qubes OS - A reasonably secure operating system -- various lang
ReconScan - Glue together pen testing workflows IFTTT style -- Python
Red Baron - Automate creating resilient, disposable, secure and agile infrastructure for red teams, Terraform based -- Golang
Red October - Go server for two-man rule style file encryption and decryption -- way cool
Red Teaming Toolkit - Collection of open source and commercial tools that aid in red team operations -- collection
Regshot - Snapshot and compare the Windows Registry for before/after analysis -- C
Rootkit Hunter - Compares hashes of important files with known good hashes that are stored in online databases -- perl shell
SalSA (Salvaging Static Analysis) - Windows PE file parsing in-browser, can be locally hosted, by the DoD -- Python
Samhain - HIDS, file integrity checker, rootkit detection, log file monitoring, and more -- C
scrub - Supports many disk-wiping standards including military / government grade wipes -- built-in
SecLists - Collection of multiple types of lists used during security assessments collected in one place -- collection
Security Onion - Linux distro for IDS, NSM, and log management -- various lang
Security Technical Implementation Guide (STIG) - Guides to securing almost every application, by the US military -- collection
SELKS - Debian based based IDS/IPS with ELK stack, installable or live CD -- various lang
Serpico - Penetration testing report generation and collaboration tool -- Ruby
simplewall - Simple app to configure Windows Filtering Platform (WFP), VERY powerful -- Windows
Snort - The classic network intrusion prevention system (NIPS) -- C
SPARTA - GUI to simplify the scanning and enumeration phases -- Python
Spiderfoot - Automate the process of gathering intelligence about a given target -- Python
SubBrute - Subdomain enumeration tool for penetration testers -- Python
sudosh2 - Records all keystrokes and output and can play back the session as just like a VCR -- C
SWORD Dropbox -- $15 OpenWRT + Pi based DIY disposable pen-test tool -- various lang
symon-config - Sysmon configuration file template with default high-quality event tracing -- XML!!!! Windows
theZoo - These are real and they are smarter than you, do not fuck around -- collection
tink - Smiple, small, secure crypto library by Google -- C++
Tripwire - File integrity checker and monitor, replacement for the now closed-source Tripwire -- C
URLquery - Free service to scan a URL for web-based malware -- in-browser
urlscan.io - Similar to URLquery -- in-browser
usbkill - Kill switch that takes action when a USB device is connected -- Python
VeraCrypt - OSS successor to and fork of TrueCrypt, supports Linux, Windows, and Mac -- C C++
VirusTotal - Allows you to upload a file and have it scanned by tons of virus scanners -- in-browser
tcpbin - A simple TCP dumping server/host for pentesting -- Python
Tomb - zsh wrapper script for cryptsetup + gpg + LUKS volumes -- shell
URL Canary - Create canary URLs so you know if someone is inspecting the source code of your applications -- in browser
VulnHub - ISOs and more for hands-on security practice -- collection
Web Application Penetration Testing Cheat Sheet - Very concise -- collection
w3af - Web application attack and audit framework, OSS vun scanner -- Python
Yaptest - Glue together and automate pentesting using IFTTT type workflows -- various lang
Zed Attack Proxy (ZAP) - Pen testing too that focues on web applications -- Java
ZMap - Scanner designed for large address spaces -- in-browser
zzuf - Transparent application input fuzzer that works by intercepting file and network operations and changing random bits in the program's input -- C

Shell Scripting and Tools

Shell scripting tutorials, collections of note, Linux shells for Windows, and misc neat tools - see also Terminal Tools and SSH Clients and Orchestration for parallel SSH tools and Regular Expressions

Advanced Bash-Scripting Guide - By the Linux Documentation Project (LDP) -- tutorial
awk Tutorial - Easy to understand awk tutorial -- tutorial
Awesome dotfiles - All kinds of . files -- collection
autojump - Small database of directories that you visited in the past, used to quickly navigate complex directory structures -- Python
Awesome Shell - Massive collection of shell tools -- collection
Babun - Pre-configured Cygwin with many more features and a better design -- various lang
Bash-it - bash version of the oh-my-zsh shell environment -- various lang
BashGuide - Targeted at beginners -- wiki
Bash Hackers Wiki - Human-readable bash documentation so you don't have to dig through the man page -- wiki
Bash Pitfalls - Common errors that bash programmers make -- wiki
bro pages - Simplifed man pages and examples -- collection
cheat - create and view interactive cheatsheets on the command-line -- Python
comm - Display lines that two files have in common (eg: the opposite of diff) -- built-in
CommandlineFu - Killer code snippets -- collection
CRUSH (Custom Reporting Utilities for SHell) - Killer toolset for working on delimited data, by Google -- C
Cygwin - GNU shell and tools for Windows -- C Windows
dotfiles by Paul Miller - Beautiful and flexible Mac terminal configuration files and utilities, ZSH-based -- shell OS X hawt
dotfiles - Unofficial guide to dotfiles on GitHub -- collection
Environment Modules - Dynamic modification of your shell environment using modules -- Tcl Windows
Explain Shell - Enter a command-line to see the help text that matches each argument -- in-browser
fu - CLI for CommandlineFu.com, allows for easy searches -- Python
fzf - Command line fuzzy finder, supports tmux/bash/zsh -- Golang
gt5 - A "du browser" in curses, handy for finding large files -- shell
icdiff - diff tool that highlights the differences -- Python OS X
moreutils - "Collection of the unix tools that nobody thought to write long ago when unix was young" -- neat
notify - Send a notification from your Linux system to an Android app on your phone, good for long running shell commands -- JavaScript Android
pigz - Parallel gzip for multi-processor/core systems -- C
pv - Shows the progress of data as it flows through a pipe -- built-in
ShellCheck - Checks shell scripts for common mistakes, essentially a linter / static analysis -- in-browser
Shell Style Guide - By Google -- collection
sysadmin-util - A collection of small but useful utilities -- perl
tldr - Simplified and community-driven man pages, cuts out a lot of cruft -- collection
Unix Toolbox - A collection of Unix/Linux/BSD commands and tasks for advanced users -- collection

Software Development Tools

Build systems, stubs/mocks, CI/CD, cheat sheets, and other - see also Git Tools and Collaboration Tools and Editors and Shell Scripting and Tools and Web and HTTP Tools and Tracing and Profiling and Web and HTTP Performance Analysis Tools

ack2 - grep-like tool designed to search source code -- perl
afl-unicorn - Fuzz any piece of binary that can be emulated by Unicorn Engine -- C
ag (aka The Silver Searcher) - Source code searching tool, a better grep -- C
Barkeep - Code review tool, kinda sorta like GitHub -- Ruby
Bazel - Google's build system -- Java
Bento - Links to tutorials based on subject (programming, sysadmin, protocols, standards, etc) -- collection
brom - Record HTTP transactions to improve security, designed for use in local environments and CI tools -- JavaScript
Buildbot - CI framework -- Python
cwrap - Wrappers for creating test scenarios and faking behavior/ stubbing, mostly network focused, by the Samba guys -- C
deployinator - Etsy's deployment framework -- Ruby gem
dev-setup - Automated setup scripts for laptop tools like Sublime Text, AWS, Spark, Android dev, and more -- collection
drone - CI platform built on Docker / containers, can also deploy to Kubernetes -- Golang
dropwizard - Simple library for building production-ready RESTful web services -- various lang
Fossil - Simple all-in-one SCM -- various lang
fswatch - Cross-platform for watching files and taking action when they change -- C++
gdb TUI - Curses / menu-based interface for GDB, much easier than REPL mode -- C
GoCI - Go continuous delivery platform by ThoughtWorks -- Java
Guard - Flexible framework to take action on file system change event -- Ruby gem
Gulp - Built system / toolkit that helps you automate time-consuming tasks in your development workflow -- JavaScript
Jenkins - The most popular CI orchestration tool, supports a billion plugins -- various lang
jenkins-job-dsl (Jenkins Job DSL Plugin) - Groovy-based DSL for writing Jenkins jobs -- Groovy
Jenkins job-config-history Plugin - Tracks changes to system and job configurations -- Java
Jenkins Job Builder - Takes simple descriptions of Jenkins jobs in YAML or JSON format and uses them to configure Jenkins -- Python pip
Jenkins Log Recorder - Helps you group relevant logs together while filtering out the noise -- Java
Jenkins Pipeline Mutlibranch Plugin - Automatically creates a new Jenkins job whenever a new branch is pushed to a source code repository -- Java
Jenkins ThinBackup - Jenkins plugin that backups configurations (not workspaces or archives) -- Java
JSON Server - Full fake REST API for quickly prototyping and mocking in 30 seconds -- JavaScript
Meld - Diff tool, recommended -- Python
MockServer - Web server to remotely or locally mock HTTP/HTTPS and similar -- Java
mountebank - Stub downstream resources for testing, supports HTTP HTTPS SMTP TCP -- JavaScript Windows OS X
Ninja - Small build system with a focus on speed -- Python
OverAPI - Large collection of cheat sheets for almost anything -- collection
PatchELF - Simple utility for modifying existing ELF executables and libraries -- C
PEview - Easily and quickly view the structure and content of Windows EXE DDL LIB Portable Executable (PE) files -- closed source
PRoot - chroot, mount --bind, and binfmt_misc without privilege/setup -- C
Proxygen - Modern C++ HTTP library, by Facebook -- C++
REST-assured - Java DSL for testing of REST services -- Java
RocksDB - Library that provides an embeddable, persistent key-value store for fast storage - by Facebook -- C++
scrypt - More secure against hardware brute-force attacks than alternatives such as PBKDF2 or bcrypt, key stretching -- C
Serverless by Design - In-browser or self-hosted GUI for making flow charts for serverless apps -- various lang
SonarQube - Platform and dashboard for managing code quality -- Ruby Java
Sonatype Nexus - Software / binary artifact storage -- Java
SourceGraph - Perhaps the best code search and navigation engine -- Golang
SymbolHound - Search engine that doesn't ignore special characters, great for programming questions -- try it
Visual Studio Code - Open Source - Open source version of Microsoft's product -- JavaScript
watchman - Watch files and take action when they change (eg: kick off the CI system), by Facebook -- C
WireMock - Flexible stubbing and mocking services -- Java

SSH Tools

Misc SSH stuff - see also Terminal Tools and SSH Clients for clients and Orchestration for parallel SSH tools and Shell Scripting and Tools

Advanced SSH Config - Enhances ssh_config file capabilities -- Python pip
autossh - Automatically restart SSH sessions that stop passing traffic -- C
Ballast (Balancing Load Across Systems) - Balance user load across SSH servers based on configured policies -- C
Corkscrew - Tunnel SSH through HTTP proxies -- C
Dropbear - Small / minimal SSH client and server, often used in IoT and embedded devices -- C
Keychain - Manage SSH and GPG keys, acts as a frontend to ssh-agent, only enter passphrase once per reboot -- shell
Match - Creates a conditional block, great for controlling actions on a per-user and/or per-host basis in sshd_config -- built-in
Mosh (Mobile Shell) - Remote shell that supports roaming (client IP address changes) and intermittent connectivity, by MIT -- C++
rssh - Restricted shell for SSH, only allows scp, sftp, rdist, rsync, and cvs -- C
scponly - Shell that only allows incoming SCP, supports chroot -- C
Shuttle - A simple SSH shortcut menu for macOS -- Objective-C
ssh-chat Instead of a shell you get a chat prompt -- Golang
ssh-ldap-helper - Store public keys in LDAP -- built-in
SSHFS - Mount remote file systems using a SSH tunnel -- built-in
sshmuxd - SSH jumphost style proxy -- Golang
sshrc - Sources the ~/.sshrc on your local computer after logging in remotely -- shell
sshttp - Port multiplexer that hides a SSH daesmon behind HTTP, HTTPS, or SMTP on a single port -- C
SSH Guard - Think fail2ban for SSH -- C
SSH Power Tool (sshpt) - Execute commands and upload files to many servers simultaneously via SSH without using pre-shared keys -- Python pip
storm - CLI and GUI tool to manage your SSH connections (add, delete, list, search) -- OS X

SSL Tools

SSL, TLS, CAs, and similar tools for interacting with HTTPS and SSL certificates - see also Web and HTTP Tools and Security Tools

BadSSL.com - Test various clients (browsers, etc) against bad SSL configs -- in-browser
BoringSSL - Google's fork of OpenSSL, does not guarantee API and ABI compatibility -- C
cfssl - PKI/TLS swiss army knife, has CLI and a HTTP API server for signing, verifying, and bundling TLS certificates -- Golang
cipherscan - Find out which SSL ciphersuites are supported by a target -- Python
Dogtag Certificate System - PKI component of FreeIPA, by Fedora -- C
Fizz - C++14 implementation of the TLS-1.3 standard, by Facebook -- C++
HSTS (HTTP Strict Transport Secuirity) - Forces browsers to interact with a site by only using HTTPS -- article
Lemur - Broker between CAs and environments providing a central portal for developers to issue TLS certificates with 'sane' defaults -- Python
Let's Encrypt - Free SSL certs from a real CA -- in-browser
LibreSSL - OpenBSD's fork of OpenSSL, Linux compatible -- C
Mozilla Server Side TLS - Mozilla's extensive server side TLS configuration guide -- wiki
Mozilla SSL Configuration Generator - Generate SSL configs for Apache, Nginx, ELB, HAproxy and more -- in-browser
nogotofail - Spot and fix weak TLS/SSL connections and sensitive cleartext traffic, by Google -- Python
Qualys SSL Server Test - Evaluates and provides recommendations for the SSL settings of any web site -- in-browser
s2n - Amazon's implementation of the TLS/SSL protocols in C99 (simple, small, fast, secure) -- C
Server Name Indication (SNI) - Think vhosts for SSL -- article
sslconfig - CloudFlare's Internet facing SSL cipher configuration, patches for Nginx and OpenSSL -- C
SSLsplit - Transparent and scalable SSL/TLS interception -- C
sslyze - Fast and full-featured SSL scanner, written in Python -- Python OS X
SSL Decoder - Decodes a SSL connection and displays certificate information, CLI -- PHP
SSL Decoder - Same as above but web based -- in-browser
stunnel - Create simple TLS tunnels for existing services (eg: telnet, nc, etc) -- C

Storage Tools

The storage junk drawer - see also Backups and Cloud File Sync and Sharing and Live CD Tools

BeeGFS - Parallel cluster file system, worth examining -- C++
CrystalDiskInfo - S.M.A.R.T. GUI tool for Windows -- closed source Windows
FlashCache - General purpose, write-back block cache -- C
fs-cache - Modern NFS client-side caching -- built-in
Linux-IO Target (LIO) - Create and share iSCSI, Fibre Channel, FC over Ethernet, and other storage targets from Linux VMs -- built-in
Linux Journal - Linux Swap Space - Superb article about Linux swap, includes some tuning parameters -- article
lsblk - List block devices -- built-in
ncdu - ncurses version of "du" -- built-in
Parted Magic - Resize, grow, shrink, clone, recovery, wiping, benchmarking, and more. Supports Linux and Windows file systems -- Windows
snapper - CLI tool to manage Btrfs snapshots, snapshot timelines, and more -- various lang
System Storage Manager (SSM) - Generic CLI for managing all types of storage (DM, LVM, multipath), added in RHEL 7 -- built-in

Storage Performance Analysis Tools

Grind your disks into dust - see also Performance Analysis Tools and Tracing and Profiling

blktrace - mount -t debugfs debugfs /sys/kernel/debug && blktrace -d /dev/md2 -o - | blkparse -i - -- article
Bonnie++ - The classic, still updated -- built-in
Connectathon Test Suite - NFS stress testing and benchmarking tools -- various lang
findswappers - perl script that identifies swapped processes -- perl
fio - Supports 19 different I/O engines (sync, mmap, libaio, posixaio, etc), very powerful -- C
Fnotifystat - Dumps the file system activity in a given period of time -- C
iometer - Multi-platform, by Intel -- C++
ioping - Monitor I/O latency in real time -- C
iorate - Originally written by EMC, now open source -- C
iotop - top for I/O requests, displays information on a per-process basis -- Python
IOzone - Supports NFS, still being updated! -- C
Threaded I/O Tester (tiobench) - Threaded I/O tester, tiotest and tiobench -- C

Terminal Tools and SSH Clients

Fancy SSH clients, terminal sharing, and similar tools - see also SSH Tools and Orchestration for parallel SSH tools and Shell Scripting and Tools

Bitvise SSH Client - Feature-rich SSH & SFTP client for Windows, free for individual use -- closed source Windows
Byobu - An enhanced version of the "screen" utility -- shell OS X
ChromaTerm-- - Pipe stdin to this program which highlights based on user defined regexs in .conf file -- C
ConnectBot - Open source SSH client for Android -- Java Android
Guacamole - Clientless (in-browser) remote desktop gateway, supports VNC and RDP -- various lang
i2cssh - csshX like ssh tool for iTerm2 -- Ruby
iTerm2 - Killer terminal replacement for Mac -- OS X -- Objective-C
KiTTY - PuTTY fork with additional features -- Windows
MobaXterm - Tabbed SSH, VNC, and RDP client for Windows, free for personal use -- closed source Windows
mRemoteNG - Open source, tabbed, multi-protocol, remote connections manager -- Windows
MTPuTTY (Multi-Tabbed PuTTY) - Multiple PuTTY sessions in a single window -- Windows
NoVNC - Client-less VNC in a web browser, uses HTML5 and WebSockets -- in-browser
PuTTY - The classic SSH client -- Windows
PuTTYtray - PuTTY in the systray + additional features -- C
reptyr - Reparent a running program to a new terminal -- C
screen - Detatch and re-attach to shell sessions while they continue to run in the background -- C
SuperPutty - Allows the PuTTY SSH client to be opened in tabs -- Windows
tmate - Instant terminal sharing, a tmux fork -- OS X
tmux - Alternative to GNU screen, also used for terminal sharing -- C
tmux-cssh - Cluster SSH for tmux -- shell
tmux Resurrect - Persists tmux environment across system restarts -- shell
Warp - Securely share your terminal, like handing a co-worker your keyboard -- Golang
WinSCP - The well-known SCP client -- C Windows
x2go - One of the best remote-desktop-over-SSH clients -- Windows OS X
Xshell - SSH client for Windows, free for personal use -- closed source Windows

Tracing and Profiling

OS kernel and process-level tracing and profiling tools - see also Performance Analysis Tools and Network Performance Analysis Tools and Web and HTTP Performance Analysis Tools and Metrics and Time Series Data and RDBMS Performance Analysis Tools

bcc - Next generation, Linux 4.x kernel tracing tool suite, uses eBPF (Extended Berkeley Packet Filters) -- C
eBPF - DTrace + SystemTap, requires 4.x kernel, mostly uses bcc -- various lang
kdump - Linux kernel dump facility (where to save it, what to save, etc) -- C
Linux Trace Toolkit - Next Generation (LLTng) - Linux kernel tracer and profiler, lower overhead than System Tap -- C
ltrace Tutorial - ltrace (library call tracer) tutorial by Red Hat -- article
lttng-analyses - Official collection of LLTNG scripts and snippets -- collection
Mastif Visualizer - Visualizer for the Valgrind's Mastiff utility -- C++
OpenSnoop - Continually monitor for file opens -- shell
OProfile - System-wide statistical profiling tool -- C
perf - User-land performance analysis tool, a sampling profiler -- C
perf-tools - Uses perf and ftrace, includes iosnoop -- Brendan Gregg
pstore - Save kernel crash info in a platform-specific persistent memory so data is not lost (eg: disks failed so write dump to NVRAM instead) -- article
Record and Replay (rr) - Record the failure once, then debug the recording deterministically, supports C and C++, by Mozilla -- C C++
strace - System call tracer for user space processes -- built-in
SystemTap (stap) - Linux kernel tracing and performance analysis tool -- C C++
Valgrind - Tool suite that includes cache profilers, heap profiles, thread race condition checkers, and more - a CPU-level emulator -- C

Two Factor Authentication

Universal 2nd Factor (U2F) is the successor to two-factor authentication / TFA / 2FA and multi-factor authentication / MFA. Avoid using SMS if possible - see also VPNs and Tunnels and Secrets Management

Authelia - 2FA and SSO for your apps via Docker on Kubernetes, supports Yubikey, Google Authenticator, and e-mail based password reset -- Golang
CentOS 7 2FA VPN - VPN with CentOS 7 + FreeRADIUS + FreeIPA + Google Authenticator -- tutorial
FreeOTP - Open source fork of Google Authenticator, by Red Hat -- C mobile
Google Authenticator - Official project, supports Android, iOS, and has a PAM module for SSH 2FA -- C
Nitrokey - Open source thumb drive for authentication -- various lang
One Time Password - PAM module allowing single-use passwords to login to a system -- C
pam-u2f - PAM module for auth via U2F compatible devices, by YubiKey -- C
privacyIDEA - All in one solution for two-factor authentication across all your organization's devices such as OTP tokens, SMS, VPNs, SSH keys, Windows, keyfob, etc -- various lang
Titan Security Key - Physical key for FIDO 2FA, unphishable (really) -- physical
W3C's Web Authentication - Standards driven, supports various tokens and OTP generators -- specification
yubico-pam - PAM module for use with YubiKey devices -- C
yubikey-full-disk-encryption - Encrypt storage on a LUKS partition using a Yubikey -- Shell
YubiKey GPG & SSH Guide - Guide to using YubiKey as a SmartCard for GPG and SSH -- tutorial

Virtualization and SDN

OS, network, and storage virtualization, emulation, and simulation including SDN, load balancers, and firewalls - see also Containers for container-only network meshes and VMware Tools

BlueStacks - Android emulator that you can run on Windows, run apps from the Play store, etc -- various lang
BusyBox - Bootable Linux with tiny versions of many common UNIX utilities in a single small executable -- C
Calico - L3 fabric that runs a vRouter on each node, supports containers -- Python
DOSbox - Open source DOS emulator, great for running old games or utilities -- C C++
Firecracker - Micro-VM for serverless computing, by Amazon -- Rust
FreeNAS - BSD-based NAS, supports ZFS -- C
GitHub Load Balancer Director - Layer 4 load balancer -- C
GNS3 - Cisco and other network simulator that runs in VirtualBox or Qemu/KVM -- Python
HAproxy - Open source software load balancer -- C
haproxyctl - Wrapper to talk to the HAProxy socket, as well as regular init (start stop restart) shit -- Ruby gem
Katran - A high performance layer 4 load balancer library, by Facebook -- C++
KVM (Kernel Virtual Machine) - The one, the only -- C
kvm-tools - CLI tools for managing qemu-kvm domains -- C
KVM Management Tools - Great list of KVM management tools on the KVM wiki, updated frequently -- collection
libvirt - Open source API, daemon and management tool, used with many virtualization solutions -- C
Linux-IO Target (LIO) - Create and share iSCSI, Fibre Channel, FC over Ethernet, and other storage targets from Linux VMs -- built-in
LVS (Linux Virtual Server) - Linux-based load balancer, also includes the IPVS kernel module -- C
Mininet - Easily setup networks for testing on your laptop with VirutalBox -- various lang
Minio - An open source object storage server compatible with Amazon S3 APIs -- Golang
ns-3 - Network simulator, mostly focuses on wireless IP such as Wi-Fi, WiMAX, or LTE and routing protocols such as OLSR and AODV -- C
Open vSwitch (OVS) - Production quality software switch -- C
OpenFiler - Linux-based NAS, supports most protocols and storage types -- C
Oracle VM VirtualBox - Easy, simple virtualization -- C C++ Windows OS X
oVirt - Virtualization management platform, the upstream for Red Hat Enterprise Virtualization (RHEV) -- Java
Packet Tracer - Cisco network simulator, by Cisco -- closed source Windows OS-X
pfsense - The best firewall software, supports appliances and live CDs -- C
phpVirtualBox - Web front-end for VirtualBox -- PHP
QEMU (Quick EMUlator) - Also supports hardware emulation (SPARC, RISC, etc) -- C
Seesaw - Load balancer based on Linux Virtual Server (LVS), by Google -- Golang
Shadow - Network simulator that runs real applications like Tor and distributed systems of thousands of nodes on a single machine -- C
Squid - Reverse proxy, caching server, web traffic filter, and more -- C++
Traefik - Modern HTTP reverse proxy and load balancer, supports many backends -- Golang
Unicorn Engine - CPU emulator framework (ARM, AArch64, M68K, Mips, Sparc, X86) via QEMU -- various lang
virt-manager - KVM / Xen / LXC GUI -- Python
WANem (Wide Area Network Emulator) - WAN emulator -- C
WINE - Compatibility layer for running Windows apps on POSIX-compliant OSes -- C OS X
Xen - It's a hypervisor! -- C
XenServer - Successor to Xen Cloud Platform (XCP) -- C
xhyve - Lightweight OS X virtualization based on bhyve -- C OS X
ZeroTier - Cloud / provider-agnostic private network backplanes, network virtualization -- C++ all platforms

VMware Tools

Mostly unofficial VMware tools and scripts - see also Virtualization and SDN

Compliance Checker for vSphere - Provides detailed compliance checks against vSphere hardening guidelines, official tool -- closed source
FastSCP - Super fast SCP client for Windows for moving stuff around in a VMware environment (ISOs, VMDKs between data stores, etc) -- closed source
Flings - Tons of very useful apps written by VMware engineers, worth exploring A++++ -- closed source? various lang
Onyx - Do something in vSphere and it will create a PowerCLI script to do that thing that you just did -- closed source PowerShell Windows
open-vm-tools - OSS alternative to VMware Guest Tools -- C
PowerCLI - VMware's CLI -- closed source
RVtools - Killer GUI for viewing information about your VMware environment -- closed source .NET Windows
RVtools Export - Wrapper script to save daily snapshots of your environment using RVtools -- PowerShell
Sexigraph - Graphite-based visualization appliance for Sexilog -- various lang
Sexilog - ELK stack virtual appliance designed for vSphere / VMware ESXi logs -- various lang
vCheck - Get an overview of a new environment or check the health of an existing one -- PowerShell
vDisk Informer - Check vDisks alignment and see if they have wasted space -- closed source Windows
vGhetto Script Repository - Various scripts from virtuallyGhetto -- various lang
VMware Community PowerPack - A variety of scripts from Virtu-al.net and now other blogs such as ict-freak.nl and ntpro.nl -- lost-to-the-internet PowerShell
VMware on Github - VMware's Github repos -- various lang
VMware Sample Exchange - Code samples & scripts by both VMware and the community -- various lang
vSphere Health Check Report - Reports a massive amount of information, run it on a schedule -- closed source perl
vSphere Mobile Watchlist - Monitor VMs on your phone -- closed source mobile

VPNs and Tunnels

VPN client & servers, tunneling proxies, DNS tunneling, simple host-to-host tunnels, and related tools - see also SSL Tools and SSH Tools and Virtualization and SDN

Algo VPN - IKEv2 Ubuntu-based strongSwan VPN server deployed to any cloud via Ansible -- Python
AutoVPN - Spin up and autoconfigure OpenVPN instances in AWS -- Python
BrowserLeaks - See if info is leaking from your browser (your real IP when you're behind a VPN, etc) -- in-browser
CentOS 7 2FA VPN - VPN with CentOS 7 + FreeRADIUS + SSSD + Google Authenticator -- stepbystep
Corkscrew - Tunnel SSH through HTTP proxies -- C
DNS Leak Test - See if DNS queries are leaking outside of your VPN / secured network -- in-browser
dnscrypt-proxy - DNS proxy, with support for modern encrypted DNS protocols such as DNSCrypt v2 and DNS-over-HTTP/2 -- Golang
dnscrypt-wrapper - Add dnscrypt support to any resolver, server-side dnscrypt proxy -- C
fwknop (FireWall KNock OPerator) - Single Packet Authorization (SPA), authoriation packet from you opens firewall rules so only you can get in -- various lang
Go HTTP Tunnel - Fast and secure reverse tunnels over HTTP/2 and TLS, share localhost without having a public IP -- Golang
IP Leak - Test to see if your browser is leaking information -- in-browser
kcptun - Secure and fast tunnel based on KCP, can increase throughput -- Golang
localtunnel - Share a HTTP/web service on your local development machine without messing with DNS and firewall settings -- JavaScript Windows OS X
MACsec aka 802.1AE - Use me for confidentiality and integrity at layer 2, useful for WAN links -- standard
Magic Wormhole - Safely and simply send arbitrary-sized files and directories (or short pieces of text) from one computer to another -- Python
n2n - L2 over L3 VPN that uses a peer-to-peer architecture -- C
nipe - A script to make Tor Network your default gateway -- perl BOOYA
OpenConnect - Supports Cisco's AnyConnect SSL VPN -- C
OpenVPN - The one and only -- C
Pritunl - Distributed enterprise VPN server built using the OpenVPN protocol, supports Google sign-in -- Python
Shadowsocks - A secure socks5 proxy, designed to protect your Internet traffic -- various lang most platforms
SoftEther - Perhaps the best VPN software out there -- C
spiped - Create encrypted pipes between socket addresses using pre-shared keys (PSKs), similar to ssh -L -- C
sshttp - Port multiplexer that hides a SSH daemon behind HTTP, HTTPS, or SMTP on a single port -- C
sshuttle - Transparent proxy server / VPN, doesn't need admin, forwards over SSH, supports DNS tunneling -- Python OS X
SSH Through or Over Proxy - How to create a HTTP(s) tunnel for your SSH traffic -- article
Streisand - Set up a server running a wide variety of privacy software, so easy that grandma can use it, Ansible-based -- Python
strongSwan - IPsec-based -- C
stunnel - Create simple TLS tunnels for existing services (eg: telnet, nc, etc) -- C
tinc - Simple, multi-platform VPN -- C
WireGuard - Performant in-kernel VPN server with DJB Crypto and very modern primitives -- C
Ubuntu IKEv2 VPN Setup - Simple script that sets up a IKEv2 VPN with strongSwan on Ubuntu -- shell

Web and HTTP Tools

RPC is dead, long live RPC - see also SSL Tools and Networking Tools

API Blueprint - Supports bindings/plugins for many APIs -- various lang
Awesome JSON - It's the new XML -- collection
Awesome Nginx - A collection of resources covering Nginx, Nginx + Lua, OpenResty and Tengine -- collection
curlish - Improved curl, includes cookie management and OAuth 2.0 support -- Python pip
Fiddler - HTTP/HTTPS debugging proxy for any browser, system or platform -- closed source
GoReplay - Capture and replay HTTP traffic for testing -- Golang
gRPC - High performance RPC via HTTP/2, by Google -- C
h2i - Go's interactive HTTP/2 console debugger, send raw frames, etc -- Golang
Hamms - Simulate/create connection failures, malformed response data, slow servers, fat headers, and more! -- Python
Hipache - Distributed HTTP and websocket proxy, supports load balancing -- JavaScript
htaccess Snippits - Huge collection of common and useful .htaccess snippets, please contribute -- collection
http-traceroute - Shows the entire route including cookies, redirects, and response codes -- Ruby
httpdiff - Perform the same reuqest against two HTTP servers and diff the results -- Golang
httpie - curl replacement with many new features -- Python
httptoolkit - Open-source HTTP(S) debugging proxy, analyzer & client -- Typescript
htty - A console application for interacting with web servers -- Ruby gem
Huginn - Build agents that perform automated tasks/workflows for you online or locally, like IFTTT -- Ruby
Insomnia REST Client - An alternative to POSTman, additional features -- Electron Windows OS X Linux
JSON Server - Full fake REST API for quickly prototyping and mocking in 30 seconds -- JavaScript
jq - Command line JSON processor and manipulator -- C
Lighthouse - Chrome extension to audit a web page for performance, accessibility, progressive web apps, and more, by Google -- in-browser
localtunnel - Share a HTTP/web service on your local development machine without messing with DNS and firewall settings -- JavaScript Windows OS X
mitmproxy - Intercept, modify, replay and save HTTP/S traffic - even edit flows on the fly -- Python pip
mountebank - Stub downstream resources for testing, supports HTTP HTTPS SMTP TCP -- JavaScript Windows OS X
Newman - CLI companion for Postman -- JavaScript
ng-admin - Add an AngularJS admin GUI to any RESTful API -- JavaScript
nghttp - CLI HTTP/2 client, similar to curl/wget and more -- C
nginxconfig - Web-based nginx config generator -- in-browser
ngrok - Reverse proxy that creates a secure tunnel from a public endpoint to a locally running web service and captures & analyzes all traffic over the tunnel for later inspection and replay -- rocks Golang
OpenResty - Turn nginx into a non-blocking API server -- C
PageKite - Makes HTTP servers or SSH publicly available on any server -- Python
POSTman - Create and share API and HTTP requests, great for testing and sharing -- Chrome
Puppeteer - Provides a high-level API to control headless Chrome over the DevTools Protocol -- JavaScript
Pushpin - Proxy server that adds WebSockets to existing request-response APIs -- C++
RapidJSON - Super fast JSON parser and generator -- C++ Windows
Redirect Detective - See the complete path a redirected URL goes through -- in-browser
Repose - REST proxy, solutions to API tasks such as auth, rate limiting, API validation, HTTP logging, and much more -- Java
Resty - CLI REST client you can use in shell/bash/zsh pipes -- shell
SecurityHeaders.io - Scan your web site's HTTP headers -- in-browser
Swagger - Popular API development library, now the OpenAPI standard -- various lang
tengine - A distribution of Nginx with some advanced features, by Alibaba -- C
tortilla - Easily wrap web APIs -- Python pip
Tyk - API gateway -- Golang
urlscan.io - Displays tons of stats and info about any given URL -- in-browser
Varnish - Caching HTTP accelerator -- C
vcr - Record and play back HTTP sessions -- Ruby gem
webhook - Super simple webhook server -- Golang
wuzz - Interactive cli tool for HTTP inspection (menu-based) -- Golang

Web and HTTP Performance Analysis Tools

Load generation, debugging, benchmarking, and profiling for SaaS, webapps, and HTTP(S) - see also Performance Analysis Tools and Network Performance Analysis Tools

Awesome Web Performance Optimization - Collection of web performance optimization (WPO) tools, articles, and more -- collection
Betwixt - Web debugging proxy with a Chrome DevTools look -- JavaScript
Brotli - Modern alternative to gzip, better packing, performs well with HTTP/2, HTTPS only -- zoooooom
django-debug-toolbar - Panels that display profiling information about the current request/response -- Python pip
Chrome DevTools - Many built-in tools for performance analysis -- mostly OSS
Gatling - HTTP, JMS, and WebSocket load generator -- Scala
Firefox Developer Tools - A full list of built-in Firefox developer tools including performance tools -- various lang
flask-debugtoolbar - The Django Debug Toolbar ported to Flask -- Python
h2load - HTTP/2 and SPDY load generation tool, part of the nghttp2 suite -- C
HAR Analyzer - HTTP Archive analyzier for troubleshooting from a browser perspective, by Google -- in-browser
Hey - HTTP load generator written in -- Golang
httperf - HTTP load generator, originally created, by HP -- C
httping - Simple program that "pings" a URL and shows response time -- C
JChav - Visualize JMeter output -- Java
Jaeger - OpenTracing compatible distributed tracing system, works well with Istio and Envoy, by Uber -- Golang
JMeter - Designed to load test functional behavior and measure performance, written in Java -- Java
Locust - Load generation tool written in Python that allows you to define user behavior -- Python
ngxtop - Real time top for nginx -- Python
OpenTracing - Vendor-neutral distributed tracing -- various lang
OpenZipkin - Distributed tracing systems for SaaS and webapps, by Twitter, based on Google's Dapper -- Scala
Packetbeat - Distributed packet monitoring system that can be used for application performance management -- Golang
PageSpeed Insights - Analyzes the content of a web page, then generates suggestions to make that page faster, by Google -- in-browser
PageSpeed Module - Open-source server modules that optimize your site automatically (nginx and Apache), by Google -- various lang
peep - Heap inspector for live memcached instances -- Ruby
phantomas - JS web performance metrics collector and monitoring tool -- JavaScript
redis-faina - Query analyzer that parses Redis' MONITOR command for counter/timing stats about query patterns, by Facebook -- Python
Siege - CLI based HTTP load generation tool, supports basic authentication, cookies, and HTTPS -- C
Speed Tracer - Helps you identify and fix performance problems in your web applications, by Google -- Chrome
Tsung - Distributed stress tester, also supports stress testing DBs -- Erlang
vegeta - HTTP load testing tool, written in Go -- Golang
Web Page Test - Free website speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds -- in-browser
wrk - Multi-threaded CLI-based HTTP load generation tool -- C
wrk2 - Fork of wrk that fixes the "coordinated omissions problem" -- C
YSlow - Analyzes web pages and why they're slow based on Yahoo!'s rules for high performance web sites, customizable -- JavaScript
UpTrends Uptime Checker - Check a URL's response time from ~30 different sites around the globe -- in-browser
Varnish Dashboard - Realtime dashboard for Varnish cache servers -- JavaScript

Misc Tools and Learning Opportunities

Everything else - see also everything else

A Practical Guide to (Correctly) Troubleshooting with Traceroute - Presentation, really digs in -- article
A Practical Introduction to Container Terminology - Concise breakdown, by Red Hat -- article
Amazon ECS Workshop - Configure GitHub, CodePipeline, CodeBuild, VPC, ALB, ECS, Autoscaling, and log aggregation using a framework called Mu to launch microservices on AWS Elastic Container Service -- tutorial
Amazon EKS Workshop - Designed to educate engineers that might not be familiar with Amazon EKS, Kubernetes, and possibly even Docker container workflow -- tutorial
An Illustrated Guide to Kubernetes Networking - See title -- article
An Introduction to Distributed Systems - by Aphyr -- tutorial
Ansible for DevOps - The recommended book to learn Ansible -- book
Ansible Interactive Tutorial - Interactive tutorials for Ansible via Docker, super simple -- tutorial
Ansible Lightbulb - Workshops, training decks, and guides, by Red Hat -- tutorials
Anti-Ablock Killer - Keep your ad-blocker active when pages take anti-blocking measures, requires Greasemonkey or similar -- JavaScript
Application Layer Transport Security - Use mutual TLS to secure RPC calls between entities, designed with containers and microservices in mind -- article
AppLock - Lock individual apps on Android -- Java
Architecture of Open Source Applications - The authors of four dozen open source applications explain how their software is structured, and why -- collection
Archive.org aka The Internet Archive aka The Wayback Machine - Yo donate, this is beyond important -- the biggest collection
AutoIT - Scriptable GUI input for Windows (think AutoHotKey) but with a BASIC-like syntax -- closed source
Automate the Boring Stuff with Python - Exceptional -- book
Awesome - Top level list of awesome lists -- collection
Awesome SRE - Too lazy to think of a description -- collection
AWS Geek - Notes and diagrams -- collection
AWS Security Workshops - An official collection by Amazon -- tutorial
AutoHotKey - Automate input (desktop and web forms, data entry, keybinds, etc) -- C++ Windows
Awesome AutoHotKey - A collection of AutoHotKey scripts and libraries -- various lang
Bandit - A "wargame" that teaches the user how to use Linux -- neat
BBR NKOTB - Excellent article that explains BBR and compares it to traditional TCP congestion and loss algorithms -- article
Beyond the 12 Factor App - Free ebook, by Pivotal -- book
Borg, Omega, and Kubernetes - Lessons Learned from 3 Container Management Systems Over a Decade - Paper by Google -- article
Caffeine - Simple menu bar app to stop your Mac from sleeping -- closed source OS X
Chaos Engineering - Building confidence in system behavior through experiments, free book by Netflix -- book
Cloud Custodian - Rules engine for managing public cloud accounts and resources via policies, by Capital One -- various lang
Cloud Design Patterns - Useful for building reliable, scalable, secure applications in the cloud, by Microsoft -- collection
Cloud Native DevOps with Kubernetes - Full book -- book
Cloud Native Landscape - A map that attempts to categorize most of the projects and product offerings in the cloud native space -- collection
Command Line Text Processing - awk grep sed etc - interactive tutorial for newbies -- tutorial
Comprehensive Python Cheatsheet - Includes many modules -- collection
Computer Science Flash Cards - As described, can be converted into an Anki deck -- Python
conserver - Virtual console server with many features (multi-user, console log history, etc) -- C
Container Training - Self paced and interactive, formerly Intro to Docker -- training
Convergent Encryption - Produces identical ciphertext from identical plaintext files, used for dedupe / space savings in the cloud -- article
Cookie Autodelete - Browser add-on that's essentially a cookie whitelist / grey list -- Firefox Chrome
Cool Store - An exercise to wire up small microservices into a larger application -- tutorial
CRIU (Checkpoint Restore in Userspace) - Freeze a process, save it to disk, then resume it later -- insane
curl Exercises - Exercises for the 'curl' command -- tutorial
Cybersecurity Canon - A Rock & Roll Hall of Fame for cybersecurity books, by Palo Alto -- collection
Dark Mode by Bernard - Simple dark mode / night mode for Firefox -- JavaScript
Databases by Daniel Soper - From the ground up, Personally recommended -- tutorial
Design Patterns for Humans - An ultra-simplified explanation of repeatable software design patterns -- article
Design Patterns - Wonderful collection of software development design patterns with examples, includes anti-patterns and refactoring guidelines -- collection
Designing Data Intensive Applications - The big ideas behind reliable, scalable, and maintable systems - highly recommened -- book
DevDocs - Documentation browser for almost every API -- collection
DevOps Conferences - Add and remove via PR, please contribute -- collection
Docker Curriculum - One-stop shop for getting your hands dirty with Docker -- tutorial
Dog vs. Cat: Docker Swarm Stacks - Examples for building full Swarm-based clusters including proxies, centralized logging, persistent storage, deployment pipelines, and more -- tutorial
Every Programmer Should Know... - A collection of (mostly) technical things every software developer should know -- collection
Everything You Should Know About Certificates and PKI - Easy to understand tutorial -- tutorial
f.lux - Changes your screen from blue light to yellow light when the sun sets to tell your brain it's night time -- closed source OS X Windows
Fossor - Automate on-call investigation steps, by LinkedIn -- Python pip
Geocities-izer - Make any HTML web page look like a Geocities page -- sweeeeeeet
go-perfbook - Outlines best practices for writing high-performance Go code -- article
Goalkicker - Free programming ebooks -- collection
Go by Example - Hands-on introduction to Go using annotated example programs -- tutorial
Go Tooling In Action - A workshop covering all the tools used in the day to day life of a Golang dev -- tutorial
Good Sleep, Good Learning, Good Life - Compiled knowledege about sleep with sources and citations -- zzz
GoodRX - Coupons for prescriptions, vaccines, and more, can be used pre-deductible, USA-centric -- ez savings
Google Advanced Operators for Web Search - Search modifiers for more accurate results, by Google -- collection
Google's Technical Development Guide - Hands on, free, self-paced courses to help you develop your programming skills -- collection
googler - Google search, news, and site search from the terminal, slick -- Python
gosu - Simple Go-based setuid+setgid+setgroups+exec for stepping down privs, use me to avoid weird su and sudo TTY bugs -- Golang
Hashicorp Learn - Official training for Vault, Consul, Terraform, Vagrant, Packer, and Nomad -- training
High Performance Browser Networking - What every web developer needs to know about the various types of networks (WiFi, 3G/4G), transport protocols (UDP, TCP, and TLS), application protocols (HTTP/1.1, HTTP/2), and APIs available in the browser (XHR, WebSocket, WebRTC, and more) -- book
Homomorphic Encryption - Allows data to be encrypted and out-sourced to 3rd parties for processing, all while encrypted (or remove HIPAA barriers) -- article
Hoopla - Digital movies, music and ebooks for USA public library members -- explore yours today
How Complex Systems Fail - Paper by MIT, a great read for operations -- article
HTTP/3 Explained - QUIC = next generation TCP via UDP to bypass TCP's bad algos, used in HTTPv3 by haxx -- book
HTTPS Everywhere - Uses client-side tricks to force misconfigured sites to use HTTPS all the time, by the EFF (donate) -- Firefox Chrome
Huginn - Build agents that perform automated tasks/workflows for you online or locally, like IFTTT -- Ruby
Interactive Coding Challenges - 120+ interactive Python coding interview challenges (algorithms and data structures), includes Anki flashcards -- Python
Interlibrary Loan - If your local library doesn't have a book or DVD in their collection they can use this service to order it from another library so you can borrow it out -- i'm learnding
Introduction to Cloud Infrastructure Technologies - Notes from the superb course on edX -- collection
Introduction to Kubernetes - Notes from the Introduction to Kubernetes course on edX -- collection
Introduction to Linux - Endorsed by Linus himself, via edX -- course
inxi - "a full featured system information script" (hardware info, etc) -- shell
JVM Anatomy Park - Anatomy of the JVM -- collection
JVM Internals - A superb explanation of how the Java JVM works in easy to understand terms -- collection
Kanopy - Streaming movies for USA public library members -- explore yours today
Katacoda - In-browser labs and exercises with modern DevOps tools -- way cool
Kubernetes Academy - k8s and containers tutorials as well as k8s certification preparation, by VMware -- tutorial
Kubernetes by Example - By the RedHat OpenShift team -- tutorial
Kubernetes Clusters for the Hobbyist - How to securely run Kubernetes on providers that don't have ELBs, private networking, or persistent distributed storage (Hetzner Cloud, DigitalOcean or Scaleway) -- guide
Kubernetes Failure Stories - Post mortems of Kubernetes outages, great way to learn -- collection
Kubernetes the Hard Way - Build Kubernetes from the ground up as a learning exercise -- tutorial
Kubernetes the Hard Way Azure - Ported to Azure -- tutorial
Kubernetes the Hard Way Vagrant - A port of Kelsey Hightower's "Kubernetes the Hard Way" tutorial to Vagrant -- tutorial
Latency: A Primer - Web-app centric, defines all the terms you need to know then puts the knowledge together -- article
LearnXinYMinutes - Super fast tutorials for almost every programming language -- collection
Libby - App for ebooks and audio books for USA public library members, from OverDrive -- explore yours today Android iOS Windows 10
Library Extension - Browser extension that shows you which Amazon books are available free at your local libraries, please donate -- closed source
Linux Network Performance Parameters - Tutorial, data flows, explinations and more -- tutorial
Linux Performance - Centralized page for all of Brendan Gregg's Linux performance material (slides videos pages etc) -- the man
Linux Tracing Workshop - Hands on exercises with perf, bcc, and similar tools -- various lang
Little Book of Python Anti-Patterns - See title -- book
Locast - Watch your local broadcast TV for free on any device, USA geo-locked, please donate -- all platforms!
Mail Tester - Test the spammyness of your e-mails -- in-browser
Managing Kubernetes - Full 2019 ebook by Heptio and O'Reilly -- book
maybe - Allows a dry run of almost any Linux binary, see the files it will modify, calls made, etc -- Python pip
Memory Management Reference - All in one reference for memory management and garbage collection -- collection
MIT OpenCourseWare - MIT's real course materials from 2400+ courses -- collection
Mjolnir - Automation for OS X, think AutoHotKey for Mac -- C OS X
MultiRBL - SMTP blackhole lookup tools -- in-browser
MX Toolbox - SMTP blacklist lookup, header analysis, and more -- in-browser
Network UPS Tools (NUT) - Manage power devices from over 100 manufacturers using a single web interface -- C Windows
Networking Cheat Sheets - Protocols, devices, ports, physical connectors, and more, by PacketLife -- collection
NoRoot Firewall - Android app that logs connections to show overly chatty background apps and more -- closed source
NoScript - JavaScript, XSS, tracker, Flash blockers and more - your condom for the Internet -- Firefox
oauth2_proxy - A reverse proxy that provides authentication with Google, Github or other provider -- Golang
oomd - Userspace OOM killer, highly configurable and much improved over the kernel's built in OOM killer -- C++
Open Source Society University (OSSU) - A complete education in computer science using free online materials -- collection
Open19 - Open data center hardware for standard size racks -- neat
OpenBMC - Framework to build a complete Linux image for a Board Management Controller (BMC), by Facebook -- C
OpenShift Interactive Learning Portal - Learn OpenShift in your web browser, by Red Hat -- tutorial
OpenShift v3 Developing Java Applications - An interactive workshop -- tutorial
OpenShift v3 DevOps Workshop - An interactive workshop -- tutorial
OpenShift v3 Ops Workshop - Admin / ops / design tasks and discussions -- tutorial
OpenShift v3 Workshop - Interactive and free, a good starting point, by Red Hat -- tutorial
OpenShift v4 Developer Preview - Give it a try -- tutorial
OpenShift v4 Training - Official, requires AWS -- tutorial
OpenShift v4 Workshop - By Red Hat -- tutorial
OpenVim - In-browser vim tutorial -- tutorial in-browser
Open Guides: AWS - Excellent summary of almost all services -- collection
Operating Systems: Three Easy Pieces - Probably the best OS book out there, free -- book
Outages.org Mailing List - Report and discuss major outages, network status updates, etc -- mailing list
OverDrive - Ebooks and audio books for USA public library members -- explore yours today
OWASP Secure Coding Practices - Quick Reference Guide -- Great cheat sheet, language-agnostic -- collection
Phil's Data Structure Zoo - Classifes some of the most popular data structures at the theoretical, implementation, and empirical levels -- collection
Pi-Hole - Ad and tracking blackhole that covers your entire network with a single device -- hardware
Play with Docker - Docker playground that allows users to run Docker commands in a matter of seconds (Alpine + Docker in Docker (DIN)) -- learning
Play with Docker Classroom - Interactive tutorials using Play with Docker (see above) -- learning
Play with Kubernetes - A simple, interactive and fun playground to learn Kubernetes in your browser, by Docker -- in-browser
PrivacyTools.io - All in one collection, web site source is on GitHub -- collection
Privacy Badger - The best in-browser privacy and anti-tracking tool, by the EFF (donate) -- Chrome Firefox
Production Readiness Checklist - Excellent checklist for pre-go-live, AWS-centric but great general advice -- collection
Puffer - Re-transmits free over-the-air broadcast television signals received by an antenna located on the campus of Stanford University, USA geo-locked, by Stanford Platform Lab and many others -- in-browser Android
repl.it - In-browser REPLs for a ton of languages -- in-browser
runwhen - Utilities for running commands at particular times, cron on steroids -- C
SaaS CTO Security Checklist - Categorizes and prioritizes actions by funding round -- collection
Scrum Guide - Explains Scrum in a concise and straightforward way in about 10 pages, by the creators -- article
Secure Messaging Apps - True comparison of the technical features and merits of various apps, which are TRULY secure? -- collection
Security 101 for SaaS Startups - Excellent checklist and guide in easy to understand terms for non-infrastructure people -- collection
Site Reliability Engineering (SRE) by Google - Full, free, online version of the O'Reilly book -- the best
Site Reliability Workbook - By Google -- book
Spectacle - Control desktop windows via keyboard shortcuts -- Objective C
StackStorm - IFTTT for Ops -- Python
Steps Recorder (aka Problem Steps Recorder) - Windows 7+, user records themselves reproducing a problem, they send video to you, you playback -- closed source
System Architecture - Great refresher, not so great for first time learners -- collection
System Design Primer - Learn how to design large-scale systems -- article
SymbolHound - Search engine that doesn't ignore special characters, great for programming questions -- try it
Teach Yourself Computer Science - 9 subjects, they choose the best free source to learn each subject and explain why that source is the best - they did the research for you -- collection
Tech Interview Handbook - SWE / dev-centric -- tutorial
The Art of Command Line - The BEST interactive Linux tutorial, newbie focused -- learn it
The Early Security Engineer’s First 90 Days Checklist - Aims to help security engineers and CISOs in early stage companies to prioritize their efforts in the first months of their new job -- list
The Illustrated TLS Connection - Every byte of a TLS connection explained and reproduced -- article
The Little Go Book - Free book, available in various formats - book
Twelve-Factor App - Language-independent rules for codebase, dependencies, build/release/run, dev and prod, logs, etc for a cloud/web-centric app -- collection
Twilight - F.lux for Android -- closed source
Two Factor Auth (2FA) - Web sites that do and don't support 2FA, organized by category, submit PRs for changes -- collection
uBlock Origin - Ad blocker, only use Origin, do not use another uBlock -- Firefox Chrome
Unix Rosetta Stone - The one and only resource for a mixed Linux/Unix environment -- translator
Use the Index, Luke - SQL indexing and tuning for developers -- collection
Vim Adventures - A game to learn vi / vim using your browser -- in-browser tutorial

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