diff --git a/babel.config.js b/babel.config.js
new file mode 100644
index 0000000000..e69128ca15
--- /dev/null
+++ b/babel.config.js
@@ -0,0 +1,13 @@
+const path = require("path");
+
+module.exports = function (api) {
+  api.cache(true);
+  return {
+    presets: [],
+    plugins: [
+      "@babel/plugin-transform-logical-assignment-operators",
+      path.resolve("./development/@babel/transform-object-hasown"),
+      "@babel/plugin-syntax-typescript",
+    ],
+  };
+};
diff --git a/development/@babel/fake.js b/development/@babel/fake.js
new file mode 100644
index 0000000000..476c2832a7
--- /dev/null
+++ b/development/@babel/fake.js
@@ -0,0 +1,3 @@
+module.exports = {
+  cache: () => {},
+};
diff --git a/development/@babel/transform-imports/index.js b/development/@babel/transform-imports/index.js
new file mode 100644
index 0000000000..b9739f896f
--- /dev/null
+++ b/development/@babel/transform-imports/index.js
@@ -0,0 +1,18 @@
+/* eslint-disable */
+/** @todo Make this work */
+module.exports = function () {
+  return {
+    visitor: {
+      async CallExpression(path) {
+        if (!path.node.callee || path.node.callee.type !== "Import") {
+          return;
+        }
+        const url = path.get("arguments.0");
+        if (url.type !== "StringLiteral") {
+          url.node.value = "";
+        }
+        url.node.value += "";
+      },
+    },
+  };
+};
diff --git a/development/@babel/transform-imports/package.json b/development/@babel/transform-imports/package.json
new file mode 100644
index 0000000000..5e55a1e866
--- /dev/null
+++ b/development/@babel/transform-imports/package.json
@@ -0,0 +1,3 @@
+{
+  "main": "./index.js"
+}
diff --git a/development/@babel/transform-object-hasown/index.js b/development/@babel/transform-object-hasown/index.js
new file mode 100644
index 0000000000..1ce2222b2a
--- /dev/null
+++ b/development/@babel/transform-object-hasown/index.js
@@ -0,0 +1,16 @@
+const t = require("@babel/core").types;
+
+module.exports = function () {
+  return {
+    visitor: {
+      CallExpression(path) {
+        if (!path.get("callee").matchesPattern("Object.hasOwn")) {
+          return;
+        }
+        path
+          .get("callee")
+          .replaceWith(t.identifier("Object.prototype.hasOwnProperty.call"));
+      },
+    },
+  };
+};
diff --git a/development/@babel/transform-object-hasown/package.json b/development/@babel/transform-object-hasown/package.json
new file mode 100644
index 0000000000..5e55a1e866
--- /dev/null
+++ b/development/@babel/transform-object-hasown/package.json
@@ -0,0 +1,3 @@
+{
+  "main": "./index.js"
+}
diff --git a/development/builder.js b/development/builder.js
index ef9fa1a0c1..77b68817cb 100644
--- a/development/builder.js
+++ b/development/builder.js
@@ -5,6 +5,13 @@ const ExtendedJSON = require("@turbowarp/json");
 const compatibilityAliases = require("./compatibility-aliases");
 const parseMetadata = require("./parse-extension-metadata");
 const { mkdirp, recursiveReadDirectory } = require("./fs-utils");
+const typescript = require("typescript");
+const tsCompilerOptions = typescript.parseConfigFileTextToJson(
+  "tsconfig.json",
+  fs.readFileSync("tsconfig.json", "utf-8")
+).config;
+const babelOptions = require("../babel.config")(require("./@babel/fake"));
+const babelCore = require("@babel/core");
 
 /**
  * @typedef {'development'|'production'|'desktop'} Mode
@@ -103,6 +110,7 @@ const insertAfterCommentsBeforeCode = (oldCode, insertCode) => {
 
 class BuildFile {
   constructor(source) {
+    this.realSourcePath = source;
     this.sourcePath = source;
   }
 
@@ -111,11 +119,11 @@ class BuildFile {
   }
 
   getLastModified() {
-    return fs.statSync(this.sourcePath).mtimeMs;
+    return fs.statSync(this.realSourcePath).mtimeMs;
   }
 
   read() {
-    return fs.readFileSync(this.sourcePath);
+    return fs.readFileSync(this.realSourcePath);
   }
 
   validate() {
@@ -131,7 +139,55 @@ class BuildFile {
   }
 }
 
-class ExtensionFile extends BuildFile {
+class JSFile extends BuildFile {
+  /**
+   * @param {string} filename Path of a TS file to set the extension of
+   * @returns {2 | 3 | false} 0 if its not a JS file extension, otherwise the length of the extension
+   */
+  static jsExtension(filename) {
+    if (filename.endsWith(".js") || filename.endsWith(".ts")) return 2;
+    if (filename.endsWith(".mjs")) return 3;
+    return false;
+  }
+  /**
+   * @param {string} filename Path of a TS file to set the extension of
+   */
+  static setExtension(filename) {
+    return (
+      filename.substring(
+        0,
+        filename.length - (JSFile.jsExtension(filename) + 1)
+      ) + ".js"
+    );
+  }
+  /**
+   * @param {string} absolutePath Full path to the .js file, eg. /home/.../extensions/fetch.js
+   */
+  constructor(absolutePath) {
+    super(absolutePath);
+    /** @type {boolean} */
+    this.isTS = this.sourcePath.endsWith(".ts");
+    this.isModule = !this.isTS && this.sourcePath.endsWith(".mjs");
+    this.sourcePath = JSFile.setExtension(this.sourcePath);
+    this.babelOptions = Object.assign(babelOptions, {
+      sourceType: this.isModule ? "module" : "unambiguous",
+      filename: this.realSourcePath,
+    });
+  }
+  read() {
+    return this.doCompile();
+  }
+  doCompile() {
+    let data = fs.readFileSync(this.realSourcePath, "utf-8");
+    if (this.isTS) {
+      data = typescript.transpileModule(data, tsCompilerOptions).outputText;
+    }
+    data = babelCore.transformSync(data, this.babelOptions).code;
+    return data;
+  }
+}
+
+class ExtensionFile extends JSFile {
   /**
    * @param {string} absolutePath Full path to the .js file, eg. /home/.../extensions/fetch.js
    * @param {string} slug Just the extension ID from the path, eg. fetch
@@ -152,7 +208,7 @@ class ExtensionFile extends BuildFile {
   }
 
   read() {
-    const data = fs.readFileSync(this.sourcePath, "utf-8");
+    const data = super.read();
 
     if (this.mode !== "development") {
       const translations = filterTranslationsByPrefix(
@@ -173,7 +229,7 @@ class ExtensionFile extends BuildFile {
   }
 
   getMetadata() {
-    const data = fs.readFileSync(this.sourcePath, "utf-8");
+    const data = fs.readFileSync(this.realSourcePath, "utf-8");
     return parseMetadata(data);
   }
 
@@ -265,7 +321,7 @@ class ExtensionFile extends BuildFile {
     };
 
     const parseTranslations = require("./parse-extension-translations");
-    const jsCode = fs.readFileSync(this.sourcePath, "utf-8");
+    const jsCode = fs.readFileSync(this.realSourcePath, "utf-8");
     const unprefixedRuntimeStrings = parseTranslations(jsCode);
     const runtimeStrings = Object.fromEntries(
       Object.entries(unprefixedRuntimeStrings).map(([key, value]) => [
@@ -727,7 +783,7 @@ class Builder {
     for (const [filename, absolutePath] of recursiveReadDirectory(
       this.extensionsRoot
     )) {
-      if (!filename.endsWith(".js")) {
+      if (!JSFile.jsExtension(filename)) {
         continue;
       }
       const extensionSlug = filename.split(".")[0];
@@ -740,7 +796,11 @@ class Builder {
         this.mode
       );
       extensionFiles[extensionSlug] = file;
-      build.files[`/${filename}`] = file;
+      if (file.isTS || file.isModule) {
+        build.files[`/${JSFile.setExtension(filename)}`] = file;
+      } else {
+        build.files[`/${filename}`] = file;
+      }
     }
 
     /** @type {Record<string, ImageFile>} */
@@ -787,6 +847,12 @@ class Builder {
     for (const [filename, absolutePath] of recursiveReadDirectory(
       this.websiteRoot
     )) {
+      if (JSFile.jsExtension(filename)) {
+        build.files[`/${JSFile.setExtension(filename)}`] = new JSFile(
+          absolutePath
+        );
+        continue;
+      }
       build.files[`/${filename}`] = new BuildFile(absolutePath);
     }
 
diff --git a/eslint.config.js b/eslint.config.js
index 89f0d99449..c0ec5c18fb 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -32,6 +32,13 @@ module.exports = [
   js.configs.recommended,
 
   // Common for all files
+  {
+    files: ["*.mjs"],
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: "module",
+    },
+  },
   {
     languageOptions: {
       ecmaVersion: 2022,
@@ -121,10 +128,6 @@ module.exports = [
       extension: {
         rules: {
           "no-new-syntax": createQueryRule([
-            {
-              selector: 'AssignmentExpression[operator="??="]',
-              message: "x ??= y syntax is too new; use x = x ?? y intead",
-            },
             {
               selector:
                 "MemberExpression[object.name=Object][property.name=hasOwn]",
@@ -304,7 +307,7 @@ module.exports = [
             "Use Scratch.vm instead of the global vm object. You also can use const vm = Scratch.vm;",
         },
       ],
-      "extension/no-new-syntax": "error",
+      "extension/no-new-syntax": "warn",
       "extension/no-xmlhttprequest": "error",
       "extension/iife": "error",
       "extension/use-scratch-vm": "error",
diff --git a/extensions/Mio/typescriptTest.ts b/extensions/Mio/typescriptTest.ts
new file mode 100644
index 0000000000..0b158bbace
--- /dev/null
+++ b/extensions/Mio/typescriptTest.ts
@@ -0,0 +1,22 @@
+// Copy of the typescript test, but in the extensions folder
+(function (Scratch: typeof globalThis.Scratch) {
+  "use strict";
+  const extensionId: string = "testtypescript";
+  const vm: VM = Scratch.vm;
+  vm.greenFlag();
+  class Test {
+    getInfo() {
+      return {
+        id: extensionId,
+        name: "Typescript",
+        blocks: [
+          {
+            blockType: Scratch.BlockType.LABEL,
+            text: "Loaded",
+          },
+        ],
+      };
+    }
+  }
+  Scratch.extensions.register(new Test());
+})(Scratch);
diff --git a/package-lock.json b/package-lock.json
index 6ea07eae5c..45a7bb5dcb 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -20,12 +20,16 @@
         "markdown-it": "^14.1.0"
       },
       "devDependencies": {
+        "@babel/core": "^7.26.9",
+        "@babel/plugin-syntax-typescript": "^7.25.9",
+        "@babel/plugin-transform-logical-assignment-operators": "^7.25.9",
         "@transifex/api": "^7.1.3",
         "eslint": "^9.21.0",
         "espree": "^9.6.1",
         "esquery": "^1.6.0",
         "prettier": "^3.5.2",
-        "spdx-expression-parse": "^4.0.0"
+        "spdx-expression-parse": "^4.0.0",
+        "typescript": "^5.7.3"
       }
     },
     "node_modules/@aashutoshrathi/word-wrap": {
@@ -37,6 +41,302 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/@ampproject/remapping": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/@ampproject/remapping/-/remapping-2.3.0.tgz",
+      "integrity": "sha512-30iZtAPgz+LTIYoeivqYo853f02jBYSd5uGnGpkFV0M3xOt9aN73erkgYAmZU43x4VfqcnLxW9Kpg3R5LC4YYw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "@jridgewell/gen-mapping": "^0.3.5",
+        "@jridgewell/trace-mapping": "^0.3.24"
+      },
+      "engines": {
+        "node": ">=6.0.0"
+      }
+    },
+    "node_modules/@babel/code-frame": {
+      "version": "7.26.2",
+      "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.26.2.tgz",
+      "integrity": "sha512-RJlIHRueQgwWitWgF8OdFYGZX328Ax5BCemNGlqHfplnRT9ESi8JkFlvaVYbS+UubVY6dpv87Fs2u5M29iNFVQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/helper-validator-identifier": "^7.25.9",
+        "js-tokens": "^4.0.0",
+        "picocolors": "^1.0.0"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/compat-data": {
+      "version": "7.26.8",
+      "resolved": "https://registry.npmjs.org/@babel/compat-data/-/compat-data-7.26.8.tgz",
+      "integrity": "sha512-oH5UPLMWR3L2wEFLnFJ1TZXqHufiTKAiLfqw5zkhS4dKXLJ10yVztfil/twG8EDTA4F/tvVNw9nOl4ZMslB8rQ==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/core": {
+      "version": "7.26.9",
+      "resolved": "https://registry.npmjs.org/@babel/core/-/core-7.26.9.tgz",
+      "integrity": "sha512-lWBYIrF7qK5+GjY5Uy+/hEgp8OJWOD/rpy74GplYRhEauvbHDeFB8t5hPOZxCZ0Oxf4Cc36tK51/l3ymJysrKw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@ampproject/remapping": "^2.2.0",
+        "@babel/code-frame": "^7.26.2",
+        "@babel/generator": "^7.26.9",
+        "@babel/helper-compilation-targets": "^7.26.5",
+        "@babel/helper-module-transforms": "^7.26.0",
+        "@babel/helpers": "^7.26.9",
+        "@babel/parser": "^7.26.9",
+        "@babel/template": "^7.26.9",
+        "@babel/traverse": "^7.26.9",
+        "@babel/types": "^7.26.9",
+        "convert-source-map": "^2.0.0",
+        "debug": "^4.1.0",
+        "gensync": "^1.0.0-beta.2",
+        "json5": "^2.2.3",
+        "semver": "^6.3.1"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/babel"
+      }
+    },
+    "node_modules/@babel/generator": {
+      "version": "7.26.9",
+      "resolved": "https://registry.npmjs.org/@babel/generator/-/generator-7.26.9.tgz",
+      "integrity": "sha512-kEWdzjOAUMW4hAyrzJ0ZaTOu9OmpyDIQicIh0zg0EEcEkYXZb2TjtBhnHi2ViX7PKwZqF4xwqfAm299/QMP3lg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/parser": "^7.26.9",
+        "@babel/types": "^7.26.9",
+        "@jridgewell/gen-mapping": "^0.3.5",
+        "@jridgewell/trace-mapping": "^0.3.25",
+        "jsesc": "^3.0.2"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/helper-compilation-targets": {
+      "version": "7.26.5",
+      "resolved": "https://registry.npmjs.org/@babel/helper-compilation-targets/-/helper-compilation-targets-7.26.5.tgz",
+      "integrity": "sha512-IXuyn5EkouFJscIDuFF5EsiSolseme1s0CZB+QxVugqJLYmKdxI1VfIBOst0SUu4rnk2Z7kqTwmoO1lp3HIfnA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/compat-data": "^7.26.5",
+        "@babel/helper-validator-option": "^7.25.9",
+        "browserslist": "^4.24.0",
+        "lru-cache": "^5.1.1",
+        "semver": "^6.3.1"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/helper-module-imports": {
+      "version": "7.25.9",
+      "resolved": "https://registry.npmjs.org/@babel/helper-module-imports/-/helper-module-imports-7.25.9.tgz",
+      "integrity": "sha512-tnUA4RsrmflIM6W6RFTLFSXITtl0wKjgpnLgXyowocVPrbYrLUXSBXDgTs8BlbmIzIdlBySRQjINYs2BAkiLtw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/traverse": "^7.25.9",
+        "@babel/types": "^7.25.9"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/helper-module-transforms": {
+      "version": "7.26.0",
+      "resolved": "https://registry.npmjs.org/@babel/helper-module-transforms/-/helper-module-transforms-7.26.0.tgz",
+      "integrity": "sha512-xO+xu6B5K2czEnQye6BHA7DolFFmS3LB7stHZFaOLb1pAwO1HWLS8fXA+eh0A2yIvltPVmx3eNNDBJA2SLHXFw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/helper-module-imports": "^7.25.9",
+        "@babel/helper-validator-identifier": "^7.25.9",
+        "@babel/traverse": "^7.25.9"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      },
+      "peerDependencies": {
+        "@babel/core": "^7.0.0"
+      }
+    },
+    "node_modules/@babel/helper-plugin-utils": {
+      "version": "7.26.5",
+      "resolved": "https://registry.npmjs.org/@babel/helper-plugin-utils/-/helper-plugin-utils-7.26.5.tgz",
+      "integrity": "sha512-RS+jZcRdZdRFzMyr+wcsaqOmld1/EqTghfaBGQQd/WnRdzdlvSZ//kF7U8VQTxf1ynZ4cjUcYgjVGx13ewNPMg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/helper-string-parser": {
+      "version": "7.25.9",
+      "resolved": "https://registry.npmjs.org/@babel/helper-string-parser/-/helper-string-parser-7.25.9.tgz",
+      "integrity": "sha512-4A/SCr/2KLd5jrtOMFzaKjVtAei3+2r/NChoBNoZ3EyP/+GlhoaEGoWOZUmFmoITP7zOJyHIMm+DYRd8o3PvHA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/helper-validator-identifier": {
+      "version": "7.25.9",
+      "resolved": "https://registry.npmjs.org/@babel/helper-validator-identifier/-/helper-validator-identifier-7.25.9.tgz",
+      "integrity": "sha512-Ed61U6XJc3CVRfkERJWDz4dJwKe7iLmmJsbOGu9wSloNSFttHV0I8g6UAgb7qnK5ly5bGLPd4oXZlxCdANBOWQ==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/helper-validator-option": {
+      "version": "7.25.9",
+      "resolved": "https://registry.npmjs.org/@babel/helper-validator-option/-/helper-validator-option-7.25.9.tgz",
+      "integrity": "sha512-e/zv1co8pp55dNdEcCynfj9X7nyUKUXoUEwfXqaZt0omVOmDe9oOTdKStH4GmAw6zxMFs50ZayuMfHDKlO7Tfw==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/helpers": {
+      "version": "7.26.9",
+      "resolved": "https://registry.npmjs.org/@babel/helpers/-/helpers-7.26.9.tgz",
+      "integrity": "sha512-Mz/4+y8udxBKdmzt/UjPACs4G3j5SshJJEFFKxlCGPydG4JAHXxjWjAwjd09tf6oINvl1VfMJo+nB7H2YKQ0dA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/template": "^7.26.9",
+        "@babel/types": "^7.26.9"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/parser": {
+      "version": "7.26.9",
+      "resolved": "https://registry.npmjs.org/@babel/parser/-/parser-7.26.9.tgz",
+      "integrity": "sha512-81NWa1njQblgZbQHxWHpxxCzNsa3ZwvFqpUg7P+NNUU6f3UU2jBEg4OlF/J6rl8+PQGh1q6/zWScd001YwcA5A==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/types": "^7.26.9"
+      },
+      "bin": {
+        "parser": "bin/babel-parser.js"
+      },
+      "engines": {
+        "node": ">=6.0.0"
+      }
+    },
+    "node_modules/@babel/plugin-syntax-typescript": {
+      "version": "7.25.9",
+      "resolved": "https://registry.npmjs.org/@babel/plugin-syntax-typescript/-/plugin-syntax-typescript-7.25.9.tgz",
+      "integrity": "sha512-hjMgRy5hb8uJJjUcdWunWVcoi9bGpJp8p5Ol1229PoN6aytsLwNMgmdftO23wnCLMfVmTwZDWMPNq/D1SY60JQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/helper-plugin-utils": "^7.25.9"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      },
+      "peerDependencies": {
+        "@babel/core": "^7.0.0-0"
+      }
+    },
+    "node_modules/@babel/plugin-transform-logical-assignment-operators": {
+      "version": "7.25.9",
+      "resolved": "https://registry.npmjs.org/@babel/plugin-transform-logical-assignment-operators/-/plugin-transform-logical-assignment-operators-7.25.9.tgz",
+      "integrity": "sha512-wI4wRAzGko551Y8eVf6iOY9EouIDTtPb0ByZx+ktDGHwv6bHFimrgJM/2T021txPZ2s4c7bqvHbd+vXG6K948Q==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/helper-plugin-utils": "^7.25.9"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      },
+      "peerDependencies": {
+        "@babel/core": "^7.0.0-0"
+      }
+    },
+    "node_modules/@babel/template": {
+      "version": "7.26.9",
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+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/code-frame": "^7.26.2",
+        "@babel/parser": "^7.26.9",
+        "@babel/types": "^7.26.9"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/traverse": {
+      "version": "7.26.9",
+      "resolved": "https://registry.npmjs.org/@babel/traverse/-/traverse-7.26.9.tgz",
+      "integrity": "sha512-ZYW7L+pL8ahU5fXmNbPF+iZFHCv5scFak7MZ9bwaRPLUhHh7QQEMjZUg0HevihoqCM5iSYHN61EyCoZvqC+bxg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/code-frame": "^7.26.2",
+        "@babel/generator": "^7.26.9",
+        "@babel/parser": "^7.26.9",
+        "@babel/template": "^7.26.9",
+        "@babel/types": "^7.26.9",
+        "debug": "^4.3.1",
+        "globals": "^11.1.0"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
+    "node_modules/@babel/traverse/node_modules/globals": {
+      "version": "11.12.0",
+      "resolved": "https://registry.npmjs.org/globals/-/globals-11.12.0.tgz",
+      "integrity": "sha512-WOBp/EEGUiIsJSp7wcv/y6MO+lV9UoncWqxuFfm8eBwzWNgyfBd6Gz+IeKQ9jCmyhoH99g15M3T+QaVHFjizVA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=4"
+      }
+    },
+    "node_modules/@babel/types": {
+      "version": "7.26.9",
+      "resolved": "https://registry.npmjs.org/@babel/types/-/types-7.26.9.tgz",
+      "integrity": "sha512-Y3IR1cRnOxOCDvMmNiym7XpXQ93iGDDPHx+Zj+NM+rg0fBaShfQLkg+hKPaZCEvg5N/LeCo4+Rj/i3FuJsIQaw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@babel/helper-string-parser": "^7.25.9",
+        "@babel/helper-validator-identifier": "^7.25.9"
+      },
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
     "node_modules/@eslint-community/eslint-utils": {
       "version": "4.4.0",
       "resolved": "https://registry.npmjs.org/@eslint-community/eslint-utils/-/eslint-utils-4.4.0.tgz",
@@ -240,6 +540,59 @@
         "url": "https://github.com/sponsors/nzakas"
       }
     },
+    "node_modules/@jridgewell/gen-mapping": {
+      "version": "0.3.8",
+      "resolved": "https://registry.npmjs.org/@jridgewell/gen-mapping/-/gen-mapping-0.3.8.tgz",
+      "integrity": "sha512-imAbBGkb+ebQyxKgzv5Hu2nmROxoDOXHh80evxdoXNOrvAnVx7zimzc1Oo5h9RlfV4vPXaE2iM5pOFbvOCClWA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@jridgewell/set-array": "^1.2.1",
+        "@jridgewell/sourcemap-codec": "^1.4.10",
+        "@jridgewell/trace-mapping": "^0.3.24"
+      },
+      "engines": {
+        "node": ">=6.0.0"
+      }
+    },
+    "node_modules/@jridgewell/resolve-uri": {
+      "version": "3.1.2",
+      "resolved": "https://registry.npmjs.org/@jridgewell/resolve-uri/-/resolve-uri-3.1.2.tgz",
+      "integrity": "sha512-bRISgCIjP20/tbWSPWMEi54QVPRZExkuD9lJL+UIxUKtwVJA8wW1Trb1jMs1RFXo1CBTNZ/5hpC9QvmKWdopKw==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.0.0"
+      }
+    },
+    "node_modules/@jridgewell/set-array": {
+      "version": "1.2.1",
+      "resolved": "https://registry.npmjs.org/@jridgewell/set-array/-/set-array-1.2.1.tgz",
+      "integrity": "sha512-R8gLRTZeyp03ymzP/6Lil/28tGeGEzhx1q2k703KGWRAI1VdvPIXdG70VJc2pAMw3NA6JKL5hhFu1sJX0Mnn/A==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.0.0"
+      }
+    },
+    "node_modules/@jridgewell/sourcemap-codec": {
+      "version": "1.5.0",
+      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.0.tgz",
+      "integrity": "sha512-gv3ZRaISU3fjPAgNsriBRqGWQL6quFx04YMPW/zD8XMLsU32mhCCbfbO6KZFLjvYpCZ8zyDEgqsgf+PwPaM7GQ==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/@jridgewell/trace-mapping": {
+      "version": "0.3.25",
+      "resolved": "https://registry.npmjs.org/@jridgewell/trace-mapping/-/trace-mapping-0.3.25.tgz",
+      "integrity": "sha512-vNk6aEwybGtawWmy/PzwnGDOjCkLWSD2wqvjGGAgOAwCGWySYXfYoxt00IJkTF+8Lb57DwOb3Aa0o9CApepiYQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@jridgewell/resolve-uri": "^3.1.0",
+        "@jridgewell/sourcemap-codec": "^1.4.14"
+      }
+    },
     "node_modules/@transifex/api": {
       "version": "7.1.3",
       "resolved": "https://registry.npmjs.org/@transifex/api/-/api-7.1.3.tgz",
@@ -420,6 +773,39 @@
         "concat-map": "0.0.1"
       }
     },
+    "node_modules/browserslist": {
+      "version": "4.24.4",
+      "resolved": "https://registry.npmjs.org/browserslist/-/browserslist-4.24.4.tgz",
+      "integrity": "sha512-KDi1Ny1gSePi1vm0q4oxSF8b4DR44GF4BbmS2YdhPLOEqd8pDviZOGH/GsmRwoWJ2+5Lr085X7naowMwKHDG1A==",
+      "dev": true,
+      "funding": [
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/browserslist"
+        },
+        {
+          "type": "tidelift",
+          "url": "https://tidelift.com/funding/github/npm/browserslist"
+        },
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/ai"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "caniuse-lite": "^1.0.30001688",
+        "electron-to-chromium": "^1.5.73",
+        "node-releases": "^2.0.19",
+        "update-browserslist-db": "^1.1.1"
+      },
+      "bin": {
+        "browserslist": "cli.js"
+      },
+      "engines": {
+        "node": "^6 || ^7 || ^8 || ^9 || ^10 || ^11 || ^12 || >=13.7"
+      }
+    },
     "node_modules/bytes": {
       "version": "3.1.2",
       "resolved": "https://registry.npmjs.org/bytes/-/bytes-3.1.2.tgz",
@@ -456,6 +842,27 @@
         "node": ">=6"
       }
     },
+    "node_modules/caniuse-lite": {
+      "version": "1.0.30001701",
+      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001701.tgz",
+      "integrity": "sha512-faRs/AW3jA9nTwmJBSO1PQ6L/EOgsB5HMQQq4iCu5zhPgVVgO/pZRHlmatwijZKetFw8/Pr4q6dEN8sJuq8qTw==",
+      "dev": true,
+      "funding": [
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/browserslist"
+        },
+        {
+          "type": "tidelift",
+          "url": "https://tidelift.com/funding/github/npm/caniuse-lite"
+        },
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/ai"
+        }
+      ],
+      "license": "CC-BY-4.0"
+    },
     "node_modules/chalk": {
       "version": "4.1.2",
       "resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
@@ -525,6 +932,13 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/convert-source-map": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/convert-source-map/-/convert-source-map-2.0.0.tgz",
+      "integrity": "sha512-Kvp459HrV2FEJ1CAsi1Ku+MY3kasH19TFykTz2xWmMeq6bk2NU3XXvfJ+Q61m0xktWwt+1HSYf3JZsTms3aRJg==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/cookie": {
       "version": "0.7.1",
       "resolved": "https://registry.npmjs.org/cookie/-/cookie-0.7.1.tgz",
@@ -640,6 +1054,13 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/electron-to-chromium": {
+      "version": "1.5.107",
+      "resolved": "https://registry.npmjs.org/electron-to-chromium/-/electron-to-chromium-1.5.107.tgz",
+      "integrity": "sha512-dJr1o6yCntRkXElnhsHh1bAV19bo/hKyFf7tCcWgpXbuFIF0Lakjgqv5LRfSDaNzAII8Fnxg2tqgHkgCvxdbxw==",
+      "dev": true,
+      "license": "ISC"
+    },
     "node_modules/encodeurl": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/encodeurl/-/encodeurl-2.0.0.tgz",
@@ -678,6 +1099,16 @@
         "node": ">= 0.4"
       }
     },
+    "node_modules/escalade": {
+      "version": "3.2.0",
+      "resolved": "https://registry.npmjs.org/escalade/-/escalade-3.2.0.tgz",
+      "integrity": "sha512-WUj2qlxaQtO4g6Pq5c29GTcWGDyd8itL8zTlipgECz3JesAiiOKotd8JU6otB3PACgG6xkJUyVhboMS+bje/jA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/escape-html": {
       "version": "1.0.3",
       "resolved": "https://registry.npmjs.org/escape-html/-/escape-html-1.0.3.tgz",
@@ -1097,6 +1528,16 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/gensync": {
+      "version": "1.0.0-beta.2",
+      "resolved": "https://registry.npmjs.org/gensync/-/gensync-1.0.0-beta.2.tgz",
+      "integrity": "sha512-3hN7NaskYvMDLQY55gnW3NQ+mesEAepTqlg+VEbj7zzqEMBVNhzcGYYeqFo/TlYz6eQiFcp1HcsCZO+nGgS8zg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6.9.0"
+      }
+    },
     "node_modules/get-intrinsic": {
       "version": "1.2.4",
       "resolved": "https://registry.npmjs.org/get-intrinsic/-/get-intrinsic-1.2.4.tgz",
@@ -1324,6 +1765,13 @@
         "node": ">=10"
       }
     },
+    "node_modules/js-tokens": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/js-tokens/-/js-tokens-4.0.0.tgz",
+      "integrity": "sha512-RdJUflcE3cUzKiMqQgsCu06FPu9UdIJO0beYbPhHN4k6apgJtifcoCtT9bcxOpYBtpD2kCM6Sbzg4CausW/PKQ==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/js-yaml": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-4.1.0.tgz",
@@ -1337,6 +1785,19 @@
         "js-yaml": "bin/js-yaml.js"
       }
     },
+    "node_modules/jsesc": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/jsesc/-/jsesc-3.1.0.tgz",
+      "integrity": "sha512-/sM3dO2FOzXjKQhJuo0Q173wf2KOo8t4I8vHy6lF9poUp7bKT0/NHE8fPX23PwfhnykfqnC2xRxOnVw5XuGIaA==",
+      "dev": true,
+      "license": "MIT",
+      "bin": {
+        "jsesc": "bin/jsesc"
+      },
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/json-buffer": {
       "version": "3.0.1",
       "resolved": "https://registry.npmjs.org/json-buffer/-/json-buffer-3.0.1.tgz",
@@ -1356,6 +1817,19 @@
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       "dev": true
     },
+    "node_modules/json5": {
+      "version": "2.2.3",
+      "resolved": "https://registry.npmjs.org/json5/-/json5-2.2.3.tgz",
+      "integrity": "sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg==",
+      "dev": true,
+      "license": "MIT",
+      "bin": {
+        "json5": "lib/cli.js"
+      },
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/keyv": {
       "version": "4.5.4",
       "resolved": "https://registry.npmjs.org/keyv/-/keyv-4.5.4.tgz",
@@ -1407,6 +1881,16 @@
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       "dev": true
     },
+    "node_modules/lru-cache": {
+      "version": "5.1.1",
+      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-5.1.1.tgz",
+      "integrity": "sha512-KpNARQA3Iwv+jTA0utUVVbrh+Jlrr1Fv0e56GGzAFOXN7dk/FviaDW8LHmK52DlcH4WP2n6gI8vN1aesBFgo9w==",
+      "dev": true,
+      "license": "ISC",
+      "dependencies": {
+        "yallist": "^3.0.2"
+      }
+    },
     "node_modules/markdown-it": {
       "version": "14.1.0",
       "resolved": "https://registry.npmjs.org/markdown-it/-/markdown-it-14.1.0.tgz",
@@ -1512,6 +1996,13 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/node-releases": {
+      "version": "2.0.19",
+      "resolved": "https://registry.npmjs.org/node-releases/-/node-releases-2.0.19.tgz",
+      "integrity": "sha512-xxOWJsBKtzAq7DY0J+DTzuz58K8e7sJbdgwkbMWQe8UYB6ekmsQ45q0M/tJDsGaZmbC+l7n57UV8Hl5tHxO9uw==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/object-inspect": {
       "version": "1.13.2",
       "resolved": "https://registry.npmjs.org/object-inspect/-/object-inspect-1.13.2.tgz",
@@ -1625,6 +2116,13 @@
       "resolved": "https://registry.npmjs.org/path-to-regexp/-/path-to-regexp-0.1.12.tgz",
       "integrity": "sha512-RA1GjUVMnvYFxuqovrEqZoxxW5NUZqbwKtYz/Tt7nXerk0LbLblQmrsgdeOxV5SFHf0UDggjS/bSeOZwt1pmEQ=="
     },
+    "node_modules/picocolors": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
+      "integrity": "sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==",
+      "dev": true,
+      "license": "ISC"
+    },
     "node_modules/prelude-ls": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.2.1.tgz",
@@ -1771,6 +2269,16 @@
       "resolved": "https://registry.npmjs.org/safer-buffer/-/safer-buffer-2.1.2.tgz",
       "integrity": "sha512-YZo3K82SD7Riyi0E1EQPojLz7kpepnSQI9IyPbHHg1XXXevb5dJI7tpyN2ADxGcQbHG7vcyRHk0cbwqcQriUtg=="
     },
+    "node_modules/semver": {
+      "version": "6.3.1",
+      "resolved": "https://registry.npmjs.org/semver/-/semver-6.3.1.tgz",
+      "integrity": "sha512-BR7VvDCVHO+q2xBEWskxS6DJE1qRnb7DxzUrogb71CWoSficBxYsiAGd+Kl0mmq/MprG9yArRkyrQxTO6XjMzA==",
+      "dev": true,
+      "license": "ISC",
+      "bin": {
+        "semver": "bin/semver.js"
+      }
+    },
     "node_modules/send": {
       "version": "0.19.0",
       "resolved": "https://registry.npmjs.org/send/-/send-0.19.0.tgz",
@@ -1974,6 +2482,20 @@
         "node": ">= 0.6"
       }
     },
+    "node_modules/typescript": {
+      "version": "5.7.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.7.3.tgz",
+      "integrity": "sha512-84MVSjMEHP+FQRPy3pX9sTVV/INIex71s9TL2Gm5FG/WG1SqXeKyZ0k7/blY/4FdOzI12CBy1vGc4og/eus0fw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    },
     "node_modules/uc.micro": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/uc.micro/-/uc.micro-2.1.0.tgz",
@@ -1987,6 +2509,37 @@
         "node": ">= 0.8"
       }
     },
+    "node_modules/update-browserslist-db": {
+      "version": "1.1.3",
+      "resolved": "https://registry.npmjs.org/update-browserslist-db/-/update-browserslist-db-1.1.3.tgz",
+      "integrity": "sha512-UxhIZQ+QInVdunkDAaiazvvT/+fXL5Osr0JZlJulepYu6Jd7qJtDZjlur0emRlT71EN3ScPoE7gvsuIKKNavKw==",
+      "dev": true,
+      "funding": [
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/browserslist"
+        },
+        {
+          "type": "tidelift",
+          "url": "https://tidelift.com/funding/github/npm/browserslist"
+        },
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/ai"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "escalade": "^3.2.0",
+        "picocolors": "^1.1.1"
+      },
+      "bin": {
+        "update-browserslist-db": "cli.js"
+      },
+      "peerDependencies": {
+        "browserslist": ">= 4.21.0"
+      }
+    },
     "node_modules/uri-js": {
       "version": "4.4.1",
       "resolved": "https://registry.npmjs.org/uri-js/-/uri-js-4.4.1.tgz",
@@ -2028,6 +2581,13 @@
         "node": ">= 8"
       }
     },
+    "node_modules/yallist": {
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/yallist/-/yallist-3.1.1.tgz",
+      "integrity": "sha512-a4UGQaWPH59mOXUYnAG2ewncQS4i4F43Tv3JoAM+s2VDAmS9NsK8GpDMLrCHPksFT7h3K6TOoUNn2pb7RoXx4g==",
+      "dev": true,
+      "license": "ISC"
+    },
     "node_modules/yocto-queue": {
       "version": "0.1.0",
       "resolved": "https://registry.npmjs.org/yocto-queue/-/yocto-queue-0.1.0.tgz",
diff --git a/package.json b/package.json
index 52f5ffc68c..513c329c14 100644
--- a/package.json
+++ b/package.json
@@ -37,12 +37,16 @@
     "markdown-it": "^14.1.0"
   },
   "devDependencies": {
+    "@babel/core": "^7.26.9",
+    "@babel/plugin-syntax-typescript": "^7.25.9",
+    "@babel/plugin-transform-logical-assignment-operators": "^7.25.9",
     "@transifex/api": "^7.1.3",
     "eslint": "^9.21.0",
     "espree": "^9.6.1",
     "esquery": "^1.6.0",
     "prettier": "^3.5.2",
-    "spdx-expression-parse": "^4.0.0"
+    "spdx-expression-parse": "^4.0.0",
+    "typescript": "^5.7.3"
   },
   "private": true
 }
diff --git a/website/test/babel-transpile.mjs b/website/test/babel-transpile.mjs
new file mode 100644
index 0000000000..caa0a44918
--- /dev/null
+++ b/website/test/babel-transpile.mjs
@@ -0,0 +1,38 @@
+/** @fileoverview @module */
+/** 
+ * @todo
+ */
+
+// @ts-ignore bleh
+// import htm from 'https://unpkg.com/htm?module'
+
+/* globals Scratch */
+(async function (Scratch) {
+  "use strict";
+  const extensionId = "testBabel";
+  let a, b;
+  a ??= {};
+  b ||= 5;
+  // @ts-ignore TS2550 TS6133
+  const _wow = Object.hasOwn(a, 'test');
+  // @ts-ignore TS1323 TS2792
+  const htm = (await import('https://unpkg.com/htm?module')).default;
+  console.log(htm.call(function h(type, props, ...children) {
+    return { type, props, children };
+  }, '<div>test</div>'));
+  class Test {
+    getInfo() {
+      return {
+        id: extensionId,
+        name: "Babel test",
+        blocks: [
+          {
+            blockType: Scratch.BlockType.LABEL,
+            text: "Loaded",
+          },
+        ],
+      };
+    }
+  }
+  Scratch.extensions.register(new Test());
+})(Scratch);
diff --git a/website/test/typescript.ts b/website/test/typescript.ts
new file mode 100644
index 0000000000..f2a4fbe1f5
--- /dev/null
+++ b/website/test/typescript.ts
@@ -0,0 +1,21 @@
+(function (Scratch: typeof globalThis.Scratch) {
+  "use strict";
+  const extensionId: string = "testtypescript";
+  const vm: VM = Scratch.vm;
+  vm.greenFlag();
+  class Test {
+    getInfo() {
+      return {
+        id: extensionId,
+        name: "Typescript",
+        blocks: [
+          {
+            blockType: Scratch.BlockType.LABEL,
+            text: "Loaded",
+          },
+        ],
+      };
+    }
+  }
+  Scratch.extensions.register(new Test());
+})(Scratch);