Chrome extensions coming to Firefox as Mozilla unveils major changes

Mozilla today announces a series of important changes that affect Firefox add-ons. The good news? Add-ons should be reviewed faster, they will be more secure, and a new API means that Chrome extensions can be more easily ported across. But, of course, there is also bad news.

The bad news for developers is that Mozilla is switching to new technologies -- Electrolysis and Servo -- and this means that work will have to be done on existing extensions to ensure compatibility. In the switchover, it is likely that a large number of older add-ons will simply not be updated, but with a 12 to 18 month timescale for phasing out XPCOM and XUL means there is plenty of time for other developers to come up with alternatives to projects that have been abandoned and will no longer work.

It is the deprecation of XPCOM and XUL that's the really big news today. This is a fundamental change to the basis of Firefox and its ramifications are huge. While the current structure of Firefox makes it highly customizable, it also lacks modularity, and can be slow to develop. Mozilla recognizes that switching to Electrolysis and Servo is a massive change that could cause problems in the short terms.

Writing on the Mozilla Add-ons Blog, Kev Needham says:

A major challenge we face is that many Firefox add-ons cannot possibly be built using either WebExtensions or the SDK as they currently exist. Over the coming year, we will seek feedback from the development community, and will continue to develop and extend the WebExtension API to support as much of the functionality needed by the most popular Firefox extensions as possible.

It is the adoption of the WebExtensions API that should see extensions coming across from other browsers to Firefox. While not identical, it is "largely compatible with the model used by Chrome and Opera".

Starting with Firefox 41 -- due for release on 22 September -- developers will have to get their extensions signed and validated by Mozilla. For developers currently producing add-ons just for Firefox, the move to WenExtensions will involve quite a lot of work, but it will be easier for those already coding for Chrome.

This is just the start of a period of intense upheaval. Mozilla says:

The strategy announced here necessarily involves a lot of trade-offs. Developers who already support Chrome extensions will benefit since they will have one codebase to support instead of two. Developers of Firefox-only add-ons will have to make changes. Those changes may require considerable development effort up-front, but we feel the end result will be worth that effort for both Firefox’s users and developers.

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