Languages and frameworks guide - Extension.js

Choose the right language and UI framework strategy for your extension surfaces, then use Extension.js defaults to keep setup minimal.

Choose by goal

Goal	Start here
Strong typing and safer refactors	TypeScript
Rich UI components with large ecosystem	React
Smaller React-like runtime	Preact
Vue single-file component workflow	Vue.js
Compiled components with minimal runtime	Svelte
Modern module syntax	ECMAScript modules
Scoped styling by default	CSS Modules
Sass or Less styling workflows	Sass, Less
Browser-safe Node compatibility decisions	Node APIs in browser extensions
Performance-heavy wasm workloads	WebAssembly

Suggested progression

Choose language/runtime (TypeScript, React, Preact, Vue, or Svelte).
Choose styling model (CSS Modules, Sass, or Less).
Add build/runtime constraints (Node APIs, WebAssembly) only when needed.

JSX pages compile for the framework the project installs: React, Preact, and Vue (through vue/jsx-runtime). Svelte components are not JSX and keep compiling through svelte-loader. The parser follows the file extension: .tsx and .jsx files parse JSX, and a .ts file never does.

Next steps

Add ecosystem tooling in Integrations.
Keep command usage clear in Commands reference.