- Competitive Programming
- [Problem Sets] (#problem-sets)
- 4Clojure
- Codeabbey
- Codechef
- Codeeval
- Codeforces
- Coderbyte
- Codewars
- Codingame
- Facebook Hackercup
- Hackerrank
- Hello World Open
- Internet Problem Solving Contest
- Just another Golf Coding
- Microcorruption
- Saratov State University
- Topcoder
- Anarchy Golf
- CareerCup
- Caribbean Online Judge
- CheckIO
- CodeHunt
- Codility
- Coding Bat
- Exercism
- Google Code Jam - Practise
- Hacker.org
- HackerEarth
- Leetcode
- Mathproblem of the Month - Bilkent University
- PEG Judge
- PKU Online Judge
- Ponder This!
- ProblemBook.NET
- Project Euler
- Python Practice Projects
- Rosalind
- Sphere Online Judge
- TalentBuddy
- Timus Online Judge
- URI Online Judge
- UVa Online Judge