Skip to main content
Build and package the same extension for multiple browsers with predictable outputs. Ship the same extension to Chrome, Edge, and Firefox without maintaining separate build scripts. Extension.js runs production builds per target and writes artifacts to dist/<browser>. It can also generate zip packages for distribution.

​
How it works

Run a production build:
The default browser target is chromium unless you override it.

​
Browser selection

You can target a specific browser/engine:
Supported values include:
  • chrome
  • edge
  • firefox
  • chromium
  • chromium-based
  • gecko-based / firefox-based (aliases)
You can also run a build matrix in one command:
This builds sequentially for chrome, edge, and firefox.

​
Output layout

Each target writes to its own folder:
  • dist/chrome
  • dist/edge
  • dist/firefox
  • dist/chromium
  • dist/chromium-based
  • dist/gecko-based
The folder is always named after the requested target, even when dev launches a different Chromium-family binary as a fallback. See Requested target vs. launch binary.

​
Build capabilities

​
Generating a zip file

Generate a distribution zip from each target output with --zip:
By default, the zip name uses sanitized manifest name + version, for example:
  • my-extension-1.0.0.zip
Customize filename:
This creates my-release.zip inside the target dist/<browser> folder.

​
Include source archive

Use --zip-source to generate a source archive alongside distribution output. --zip-source produces:
  • dist/<name>-<version>-source.zip

​
Polyfilling browser APIs

If your code relies on Gecko-style browser.* APIs and you need Chromium compatibility, enable --polyfill:

​
Best practices

  • Build per target in continuous integration (CI): Treat each browser output as an independent artifact.
  • Use a browser matrix command for parity checks: Catch target-specific issues early in one pipeline step.
  • Package intentionally: Use --zip for store uploads and --zip-source for traceable source artifacts.
  • Keep target configuration explicit: Use extension.config.* command/browser defaults for reproducible builds.

​
Next steps