WebExtensions

This page is an introduction to Mozilla's implementation of a new browser extension API. The goals of this API are:

• It should be easier to use.
• It must be compatible with multiprocess Firefox (Electrolysis).
• Porting add-ons to and from other browsers should be easier.
• Changes to Firefox's internal code should be less likely to break add-ons.
• It should be easier to review add-ons to reduce the backlog on addons.mozilla.org.

Much of the specifics of the new API are similar to the Chrome extension API. Google has extensive documentation on the API.

We hope to ship a preliminary version of this API in Firefox 42.

For the time being, extensions will still be packaged as .xpi files. The .xpi file will contain the same files as the Chrome extension, including manifest.json. It will also include bootstrap.js and install.rdf files that allow it to be loaded into Firefox.

List of supported APIs

• alarms
• browserAction
• extension
• i18n
• notifications
• permissions
• runtime
• storage
• tabs
• webNavigation
• webRequest
• windows

List of APIs we will likely support in the future

• bookmarks
• commands
• contextMenus
• cookies
• downloads
• history
• idle
• omnibox
• pageAction

Custom APIs for Firefox

We plan to add our own APIs based on the needs of existing Firefox add-ons.

• Sidebars
• Toolbars
• Keyboard shortcuts