Two tracks
Extension.js has two getting-started tracks. This page covers the CLI track: develop, run, and build extensions on your machine. If you instead want the hosted platform track (workspace, import or AI generation, preview, then CI build and store submission on extension.dev), see Get started with the Extension.dev platform.Who this path is for
- New to extension development: Create your first extension
- Exploring quickly with existing samples: Get started immediately
- Choosing a starting stack: Templates
- Shipping to the stores via extension.dev: Platform getting started
- Comparing frameworks (WXT, etc.): Extension.js vs WXT
First successful outcome
1
Scaffold or run an extension project
Use
extension create or choose a template to start from.2
Launch dev and load the extension
Run
extension dev and load the build output in a browser target.3
Verify update behavior
Make one change and confirm the extension reloads.
4
Build production output
Run
extension build for at least one browser.Recommended reading flow
Next steps
- Learn command choices in Commands reference.
- Configure project defaults in Extension configuration.
- Validate release readiness with Workflows.