Mozilla Firefox 57 will launch next month to the browser's stable channel. The version is a milestone release for Mozilla as it introduces new functionality.

Firefox 57 will support WebExtensions only which means that add-ons that are not will be deactivated automatically.

This is a big change for Firefox users who use add-ons. While some add-ons have been ported so that users can continue using them, others have not. Some developers stopped developing their add-ons, others cannot port their extensions due to missing APIs or because Mozilla won't add the functionality to the browser. The change affects add-ons that are not in active development anymore, as they won't be updated as well.

Find Firefox add-on replacements

Firefox 57 will move all legacy add-ons to the legacy extensions group on about:addons. These add-ons are deactivated and cannot be activated anymore.

The only two options are to remove the add-on from Firefox, or to use the "find a replacement" button to find a WebExtension that offers the functionality.

Mozilla plans to launch this in Firefox 57, which means that current Firefox Stable users cannot use the feature right now from within Firefox to find replacement extensions.

Here is what happens when you click on the find a replacement button:

1.Firefox will open the page of a WebExtension that is a compatible replacement according to Mozilla.
2.Legacy tab extensions are redirected to a collection of compatible WebExtensions as Mozilla is still working on adding the necessary APIs to the Firefox web browser.
3.If a replacement is not available, Firefox will load the featured add-ons page instead

You can browse the list of legacy add-ons and their recommended WebExtension suggestion, or enter the name of an add-on to find out whether Mozilla has a recommended in its database for it.

Firefox users may browse all compatible extensions as well. The group on the official Mozilla Add-ons website lists more than 5400 add-ons currently that are compatible with Firefox 57.

A quick test on my version of Firefox showed that replacements were not available for any of the three legacy extensions. A WebExtensions version of NoScript will be released however before the release of Firefox 57.