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.
Articles listed here provide a reference for the SDK's tools:
- Enables you to test, run, and package add-ons. cfx is is no longer supported as of Firefox 44 and no longer accepted for add-on submission, jpm should now be used instead.
- cfx to jpm
- A guide to working with jpm if you're already familiar with cfx.
- Enables your add-on to log error, warning or informational messages.
- jpm is a command-line tool that enables you to test, run, and package add-ons.
- The Node-based replacement for
cfx --force-mobile. Enables you to run and test add-ons for Firefox Mobile (aka Fennec).