The cross-browser extension framework

• Create A New Extension — How to create a new browser extension.
• Get Started Immediately — Fetch from sample and get work done.
• Start From A Template — Start developing with your favorite tool.
• I have An Extension — Use only specific parts of Extension.js.

Extension.js makes it very easy to develop cross-browser extensions.
Developers prefer it for its fast builds, unified interface, and zero configuration setup.

Use the create command to generate a new extension. Also works with pnpm, yarn, and bun.

//bash npx extension@latest create my-extension cd my-extension npm run dev //

For a preview of extensions running these technologies, see the templates website.

JavaScript latest	TypeScript latest	WASM latest	React v18+	Vue v3+	Svelte v5+	Preact v10+	Angular 👋	Solid 👋

👋 = PR Welcome!

Start developing an extension using a sample from Chrome Extension Samples

See the example below where we request the sample page-redder from Google Chrome Extension Samples.

//bash npx extension@latest dev https://github.com/GoogleChrome/chrome-extensions-samples/tree/main/functional-samples/sample.page-redder --browser=edge //

If you have an existing extension which is using a package manager, you can install the Extension.js package and manually create the scripts used to run your extension.

Step 1 - Install extension as a devDependency

//bash npm install extension@latest --save-dev //

Step 2 - Link your npm scripts with the executable Extension.js commands

//json { "scripts": { "build": "extension build", "dev": "extension dev", "preview": "extension preview" }, "devDependencies": { // ...other dependencies "extension": "latest" } } //

Done. You are all set!

• To develop the extension, run npm run dev.
• To build the extension in production mode, run npm run build.
• To visualize the extension in production mode, run npm run build and npm run preview.

Chrome ✅	Edge ✅	Firefox ✅	Opera ☑️	Safari ⛔️	Chromium ☑️

The browsers listed above represent those with official extension stores. Note that Chromium-based browsers (like Arc, Brave, Vivaldi, and many others) are theoretically supported through the Chrome/Chromium compatibility layer.

Firefox (Android) ⛔️	Safari (iOS) ⛔️

MIT (c) Cezar Augusto and the Extension.js Authors.