Firefox add-on technology is modernizing

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  • Revision id: 139942
  • Created:
  • Creator: andrewtruong
  • Comment: added link to webextensions. Compatibility milestones link. Re-organized info. Check current add-ons section inserted. do not review.
  • Reviewed: No
  • Ready for localization: No
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Add-ons are programs that add extra features to Firefox. Anyone can create an add-on and make it available to Firefox users who want to personalize their online experience.

In the past, add-ons often stopped working each time a new version of Firefox was released, because developers had to update them every six weeks to keep them compatible. To address this (and other issues), we overhauled the underlying technology for building add-ons.

Outside of rare instances, add-ons created with the new standard won’t break in new Firefox releases.

Note: Starting in Firefox 57, which will be released in November 2017, only add-ons built with this new technology will work in Firefox. These are indicated by the “Compatible with Firefox 57+” label on addons.mozilla.org (AMO).

We recommend that you install add-ons with the “Compatible with Firefox 57+” label to ensure compatibility with Firefox beyond November 2017.

This new technology is referred to as WebExtensions

If you are the developer of a legacy add-on, please visit the compatability milestones document. There are also resources availabe to help you migrate to the new standard.

Check your current add-ons

You can check to see if any of your current add-ons are built using the old technology. Add-ons built with the old technology are labeled “Legacy” on the about:addons tab.

  1. In the Firefox location bar, type about:addons and hit Enter
  2. Identify if any add-ons are labeled legacy

If any of your add-ons are labeled as legacy, check to see if there is a newer version of the add-on. You may also reach out to the developer of the add-on to notify them that their add-on will no longer work with in Firefox.