Firefox add-on technology is modernizing

Add-ons allow you to add extra features and functionality to Firefox, modify the Firefox user interface and change its appearance. There are several types of add-ons but extensions are the most common. Anyone can create an extension and make it available for download.

What's happening?

In the past, extensions 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. Since extensions could also modify Firefox internal code directly, it was possible for bad actors to include malicious code in an innocent-looking extension.

To address these issues, and as part of broader efforts to modernize Firefox as a whole, we’ve transitioned to a new framework for developing Firefox extensions. Outside of rare instances, extensions created with the new standard won’t break in new Firefox releases. You can still personalize Firefox with extensions the same way you do now, except they won’t break in new Firefox releases.

Note: Starting in Firefox 57, which will be released in November 2017, only extensions built with this new technology will work in Firefox. These are indicated by the "Compatible with Firefox 57+" label on addons.mozilla.org (AMO). Extensions built with the old technology are labeled "Legacy" in the Add-on Manager (about:addons) tab.

Keep in mind that many developers are in the process of updating to the new compatible format. Once they make the transition, your extension will automatically update and there is nothing you need to do.

If you are using legacy add-ons and want to start looking for alternatives in case they become incompatible in Firefox 57, use the extension finder utility to look up the extension you would like to replace and discover recommended replacements.

For more help, please head over to the FAQs.

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

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