diff --git a/src/engine/runtime.js b/src/engine/runtime.js
index 6fc794268f7..92e368923cd 100644
--- a/src/engine/runtime.js
+++ b/src/engine/runtime.js
@@ -22,6 +22,7 @@ const xmlEscape = require('../util/xml-escape');
 const ScratchLinkWebSocket = require('../util/scratch-link-websocket');
 const FontManager = require('./tw-font-manager');
 const fetchWithTimeout = require('../util/fetch-with-timeout');
+const platform = require('./tw-platform.js');
 
 // Virtual I/O devices.
 const Clock = require('../io/clock');
@@ -439,6 +440,11 @@ class Runtime extends EventEmitter {
          */
         this.origin = null;
 
+        /**
+         * Metadata about the platform this VM is part of.
+         */
+        this.platform = Object.assign({}, platform);
+
         this._initScratchLink();
 
         this.resetRunId();
@@ -912,6 +918,13 @@ class Runtime extends EventEmitter {
         return 'BLOCKS_NEED_UPDATE';
     }
 
+    /**
+     * Event name when platform name inside a project does not match the runtime.
+     */
+    static get PLATFORM_MISMATCH () {
+        return 'PLATFORM_MISMATCH';
+    }
+
     /**
      * How rapidly we try to step threads by default, in ms.
      */
diff --git a/src/engine/tw-platform.js b/src/engine/tw-platform.js
new file mode 100644
index 00000000000..ee6a2e2d627
--- /dev/null
+++ b/src/engine/tw-platform.js
@@ -0,0 +1,7 @@
+// Forks should change this.
+// This can be accessed externally on `vm.runtime.platform`
+
+module.exports = {
+    name: 'TurboWarp',
+    url: 'https://turbowarp.org/'
+};
diff --git a/src/serialization/sb3.js b/src/serialization/sb3.js
index b760e05bb08..bad68d84114 100644
--- a/src/serialization/sb3.js
+++ b/src/serialization/sb3.js
@@ -4,6 +4,7 @@
  * JSON and then generates all needed scratch-vm runtime structures.
  */
 
+const Runtime = require('../engine/runtime');
 const Blocks = require('../engine/blocks');
 const Sprite = require('../sprites/sprite');
 const Variable = require('../engine/variable');
@@ -794,6 +795,9 @@ const serialize = function (runtime, targetId, {allowOptimization = true} = {})
     // TW: Never include full user agent to slightly improve user privacy
     // if (typeof navigator !== 'undefined') meta.agent = navigator.userAgent;
 
+    // TW: Attach copy of platform information
+    meta.platform = Object.assign({}, runtime.platform);
+
     // Assemble payload and return
     obj.meta = meta;
 
@@ -1468,6 +1472,36 @@ const replaceUnsafeCharsInVariableIds = function (targets) {
     return targets;
 };
 
+/**
+ * @param {object} json
+ * @param {Runtime} runtime
+ * @returns {void|Promise<void>} Resolves when the user has acknowledged any compatibilities, if any exist.
+ */
+const checkPlatformCompatibility = (json, runtime) => {
+    if (!json.meta || !json.meta.platform) {
+        return;
+    }
+
+    const projectPlatform = json.meta.platform.name;
+    if (projectPlatform === runtime.platform.name) {
+        return;
+    }
+
+    let pending = runtime.listenerCount(Runtime.PLATFORM_MISMATCH);
+    if (pending === 0) {
+        return;
+    }
+
+    return new Promise(resolve => {
+        runtime.emit(Runtime.PLATFORM_MISMATCH, json.meta.platform, () => {
+            pending--;
+            if (pending === 0) {
+                resolve();
+            }
+        });
+    });
+};
+
 /**
  * Deserialize the specified representation of a VM runtime and loads it into the provided runtime instance.
  * @param  {object} json - JSON representation of a VM runtime.
@@ -1476,7 +1510,9 @@ const replaceUnsafeCharsInVariableIds = function (targets) {
  * @param {boolean} isSingleSprite - If true treat as single sprite, else treat as whole project
  * @returns {Promise.<ImportedProject>} Promise that resolves to the list of targets after the project is deserialized
  */
-const deserialize = function (json, runtime, zip, isSingleSprite) {
+const deserialize = async function (json, runtime, zip, isSingleSprite) {
+    await checkPlatformCompatibility(json, runtime);
+
     const extensions = {
         extensionIDs: new Set(),
         extensionURLs: new Map()
@@ -1484,8 +1520,10 @@ const deserialize = function (json, runtime, zip, isSingleSprite) {
 
     // Store the origin field (e.g. project originated at CSFirst) so that we can save it again.
     if (json.meta && json.meta.origin) {
+        // eslint-disable-next-line require-atomic-updates
         runtime.origin = json.meta.origin;
     } else {
+        // eslint-disable-next-line require-atomic-updates
         runtime.origin = null;
     }
 
diff --git a/test/integration/tw_platform.js b/test/integration/tw_platform.js
new file mode 100644
index 00000000000..d487cbe0b54
--- /dev/null
+++ b/test/integration/tw_platform.js
@@ -0,0 +1,161 @@
+const {test} = require('tap');
+const VM = require('../../src/virtual-machine');
+const platform = require('../../src/engine/tw-platform');
+const Clone = require('../../src/util/clone');
+
+test('the internal object', t => {
+    // the idea with this test is to make it harder for forks to screw up modifying the file
+    t.type(platform.name, 'string');
+    t.type(platform.url, 'string');
+    t.end();
+});
+
+test('vm property', t => {
+    const vm = new VM();
+    t.same(vm.runtime.platform, platform, 'copy of tw-platform.js');
+    t.not(vm.runtime.platform, platform, 'not the same object as tw-platform.js');
+    t.end();
+});
+
+test('sanitize', t => {
+    const vm = new VM();
+    vm.runtime.platform.name += ' - test';
+    const json = JSON.parse(vm.toJSON());
+    t.same(json.meta.platform, vm.runtime.platform, 'copy of runtime.platform');
+    t.not(json.meta.platform, vm.runtime.platform, 'not the same object as runtime.platform');
+    t.end();
+});
+
+const vanillaProject = {
+    targets: [
+        {
+            isStage: true,
+            name: 'Stage',
+            variables: {},
+            lists: {},
+            broadcasts: {},
+            blocks: {},
+            comments: {},
+            currentCostume: 0,
+            costumes: [
+                {
+                    name: 'backdrop1',
+                    dataFormat: 'svg',
+                    assetId: 'cd21514d0531fdffb22204e0ec5ed84a',
+                    md5ext: 'cd21514d0531fdffb22204e0ec5ed84a.svg',
+                    rotationCenterX: 240,
+                    rotationCenterY: 180
+                }
+            ],
+            sounds: [],
+            volume: 100,
+            layerOrder: 0,
+            tempo: 60,
+            videoTransparency: 50,
+            videoState: 'on',
+            textToSpeechLanguage: null
+        }
+    ],
+    monitors: [],
+    extensions: [],
+    meta: {
+        semver: '3.0.0',
+        vm: '0.2.0',
+        agent: ''
+    }
+};
+
+test('deserialize no platform', t => {
+    const vm = new VM();
+    vm.runtime.on('PLATFORM_MISMATCH', () => {
+        t.fail('Called PLATFORM_MISMATCH');
+    });
+    vm.loadProject(vanillaProject).then(() => {
+        t.end();
+    });
+});
+
+test('deserialize matching platform', t => {
+    const vm = new VM();
+    vm.runtime.on('PLATFORM_MISMATCH', () => {
+        t.fail('Called PLATFORM_MISMATCH');
+    });
+    const project = Clone.simple(vanillaProject);
+    project.meta.platform = Object.assign({}, platform);
+    vm.loadProject(project).then(() => {
+        t.end();
+    });
+});
+
+test('deserialize mismatching platform with no listener', t => {
+    const vm = new VM();
+    const project = Clone.simple(vanillaProject);
+    project.meta.platform = {
+        name: '3tw4ergo980uitegr5hoijuk;'
+    };
+    vm.loadProject(project).then(() => {
+        t.end();
+    });
+});
+
+test('deserialize mismatching platform with 1 listener', t => {
+    t.plan(2);
+    const vm = new VM();
+    vm.runtime.on('PLATFORM_MISMATCH', (pl, callback) => {
+        t.same(pl, {
+            name: 'aa',
+            url: '...'
+        });
+        t.ok('called PLATFORM_MISMATCH');
+        callback();
+    });
+    const project = Clone.simple(vanillaProject);
+    project.meta.platform = {
+        name: 'aa',
+        url: '...'
+    };
+    vm.loadProject(project).then(() => {
+        t.end();
+    });
+});
+
+test('deserialize mismatching platform with 3 listeners', t => {
+    t.plan(2);
+
+    const calls = [];
+    let expectedToLoad = false;
+    const vm = new VM();
+    vm.runtime.on('PLATFORM_MISMATCH', (_, callback) => {
+        calls.push([1, callback]);
+    });
+    vm.runtime.on('PLATFORM_MISMATCH', (_, callback) => {
+        calls.push([2, callback]);
+    });
+    vm.runtime.on('PLATFORM_MISMATCH', (_, callback) => {
+        calls.push([3, callback]);
+    });
+
+    const project = Clone.simple(vanillaProject);
+    project.meta.platform = {
+        name: ''
+    };
+    vm.loadProject(project).then(() => {
+        t.ok(expectedToLoad);
+        t.end();
+    });
+
+    // loadProject is async, may need to wait a bit
+    setTimeout(async () => {
+        t.same(calls.map(i => i[0]), [1, 2, 3], 'listeners called in correct order');
+
+        // loadProject should not finish until we call all of the listeners' callbacks
+        calls[0][1]();
+        await new Promise(resolve => setTimeout(resolve, 100));
+
+        calls[1][1]();
+        await new Promise(resolve => setTimeout(resolve, 100));
+
+        expectedToLoad = true;
+        calls[2][1]();
+    }, 0);
+});