Introduction
You build a browser extension and want to know which parts of shipping it this platform takes off your hands. Extension.dev builds your extension for every browser it declares, holds releases in channels, serves shareable previews, and submits to the stores with credentials it keeps so you enter them once.
The seam
Extension.js is the open source framework: create, dev, build, local debugging, the agent bridge. It runs on your machine, needs no account, and is documented at extension.js.org, not here.
Extension.dev begins where a token or a session is minted. If a thing works without a workspace, its docs live on the framework site. If it needs a sign-in, an access token, or a share link, its docs live here.
| Extension.js | Extension.dev | |
|---|---|---|
| What it is | Open source framework and CLI | Hosted platform |
| Where it runs | Your machine and your CI | The platform's infrastructure |
| What it does | Compiles, runs and bundles the extension | Builds, promotes releases, shares previews, submits to stores |
| Docs | extension.js.org | This site |
Every platform build runs the Extension.js compiler. The platform starts to matter when more than one person, more than one browser, or more than one store is involved.
What the platform adds
Cross browser builds from one commit. A project builds Chrome, Firefox, Edge and Safari artifacts from the same source, on the same commit, in the project's managed build repository, so build minutes never burn on your account. See Projects.
Release channels and environments. Builds carry an environment stamp, production or staging, and promote through channels that are bound to one of the two. See Environments and Channels.
Shared previews. A build renders in a browser emulator behind a link. The person who opens it installs nothing. See Share an unpublished build for review.
Store submissions. Chrome Web Store, Firefox Add-ons, Microsoft Edge Add-ons and Safari credentials are held once per project and reused by every submission. See Publishing.
Where work happens
Signed in, your work
| Surface | Use it for |
|---|---|
| console.extension.dev | Projects, builds, releases, store submissions, settings |
| extension.dev | Creating and importing, including the routes that work signed out |
Starting something
| Surface | Use it for | Guide |
|---|---|---|
| extension.dev/new | Two lanes: choose a template, or connect a GitHub repository | Quickstart |
| templates.extension.dev | The full catalog, each template running live in the page | Templates |
| extension.dev/import | Turning a repository, template, or generated artifact into a project | Import |
| code.extension.dev | Describing an extension and editing what comes back | Generate |
| themes.extension.dev | Building a browser theme against Chrome's own color math | Themes |
Showing it to someone
| Surface | Use it for | Guide |
|---|---|---|
| preview.extension.dev | The door a shared build link opens on | Share a build for review |
<workspace>.extension.dev | The public page for a released build | Public build pages |
Headless
| Surface | Use it for | Guide |
|---|---|---|
| The HTTP API | Builds, promotes and store submissions from CI or a terminal | HTTP API |
@extension.dev/mcp | The same verbs from a coding agent | MCP server |
@extension.dev/skill | Teaching the agent when to use which one | Agent skill |
When it fails
- You are looking for
create,dev,build, or hot reload. That is the framework. The docs are at extension.js.org. - You signed in and the console is empty. A new account starts with a workspace and no projects. Create one from extension.dev/new or connect a repository through Import.
- You cannot tell which site documents a feature. Ask whether it needs a session or a token. No: framework site. Yes: this one.
Next
- Quickstart to get a project building in minutes
- Projects to understand the model first