Legacy extensions for Firefox for Android


Support for extensions using XUL/XPCOM or the Add-on SDK was removed in Firefox 57, released November 2017. As there is no supported version of Firefox enabling these technologies, this page will be removed by December 2020.

Add-ons using the techniques described in this document are considered a legacy technology in Firefox. Don't use these techniques to develop new add-ons. Use WebExtensions instead. If you maintain an add-on which uses the techniques described here, consider migrating it to use WebExtensions.

Starting from Firefox 53, no new legacy add-ons will be accepted on addons.mozilla.org (AMO) for desktop Firefox and Firefox for Android.

Starting from Firefox 57, only extensions developed using WebExtensions APIs will be supported on Desktop Firefox and Firefox for Android.

Even before Firefox 57, changes coming up in the Firefox platform will break many legacy extensions. These changes include multiprocess Firefox (e10s), sandboxing, and multiple content processes. Legacy extensions that are affected by these changes should migrate to use WebExtensions APIs if they can. See the "Compatibility Milestones" document for more information.

A wiki page containing resources, migration paths, office hours, and more, is available to help developers transition to the new technologies.


This page, and its subpages, describe how to develop Firefox for Android add-ons using legacy techniques. These techniques will stop working in Firefox 57. You will still be able to use WebExtensions to develop add-ons for Firefox for Android.

Add-ons that work with desktop Firefox do not automatically work in Firefox for Android:

  • There is no visible XUL in the UI, so you can't use an overlay to create the UI.
  • Internal code and objects, like gBrowser, do not exist. Look at the Firefox on Android browser.js file to learn about the internals. Much of the same fundamental functionality exists.
  • Services like nsIPromptService and nsIAlertsService are implemented to use native Android UI.
  • There is a simple JavaScript object, called NativeWindow, that allows you to manipulate parts of the native Android UI.

The following articles provide help with developing extensions for Firefox on Android. In addition, please refer to the general extension documentation that applies to all Mozilla applications.


Setting up your desktop to write addons and push them to device, and how to test snippets from Desktop straight on your connected device.
Debugging Firefox for Android with WebIDE
Article from the Prerequisites tutorial, add-on debugging and snippet testing is not possible without the WebIDE.
Developing, packaging and installing a simple add-on for Firefox for Android.
Firefox Hub Walkthrough
How to develop a Firefox Hub add-on to add content to the Firefox for Android home page.
Add-on SDK
How to develop Firefox for Android add-ons using the Add-on SDK.

Sample code

Code Snippets
Code samples for common tasks.
Initialization and Cleanup
How to initialize your add-on when it is started and clean up when it is shut down.
Firefox for Android Add-ons Github Repo
A collection of JS modules, sample code, and boilerplate repos to help you build add-ons for Firefox for Android.

API reference

Create native Android UI widgets.
Access browser tabs and the web content they host.
Show native Android dialogs.
Query and launch native apps installed on the system.
Use extended properties for Android system notifications.
Customize the home page.
Store data to display on the home page.
Display page-specific actions in the URL bar.
Tap into the native Java Android API from addons.
Play sounds in the browser simply.