Mozilla wants to make Chrome Extension ports to Firefox easier
Add-ons are one of the cornerstones of the Firefox web browser. I know several Firefox users who stick with the browser because of extensions that they don't want to browse the web without with.
Some developers moved from Firefox to Chrome when Google started to introduce extension support in the web browser while others started to develop for Chrome right away.
Most extension developers produced add-ons for Firefox in the beginning but extension support in Chrome split the development community in the process.
Some extensions get ported to Firefox as well by developers while others are only available for Chrome and not Mozilla's browser.
That's something that Mozilla plans to change by improving how Chrome extensions get ported to the Firefox browser.
The main goal of the project is to allow Chrome developers to port their extensions to Firefox with minimal effort.
The meta bug links to others that add functionality to Firefox to improve the porting of Chrome extensions. Most bugs add functionality to Firefox that Chrome supports but Firefox does not, for instance a webRequest-like or webNavigation API.
Adding support for Chrome-specific APIs and features makes it easier for Chrome developers to port their extensions to Firefox as they don't have to write workarounds anymore for code that makes use of Chrome-specific features.
Mozilla released a tool on Github, Chrome Tailor, which turns Chrome extensions into Firefox add-ons. The command line tool works only in Firefox 38 or later currently and is limited to a set of Google Chrome APIs that Mozilla has already implemented in Firefox.
The full list is provided on the Chrome Tailor project website. This means that while you may be able to port some extensions to Firefox using the program, you will run into issues with others. Basically, if an extension uses an API that Chrome supports but Firefox does not it won't work.
While designed for extension developers, it is theoretically possible for anyone to port Chrome extensions to Firefox this way provided they meet the requirements outlined above.
Closing Words
Neither Mozilla nor Google have released extension statistics which means that it is unclear how many get released and used on either system.
It is clear that Firefox lost add-on developers to Chrome however and Mozilla's plan to increase the number of ports from Chrome makes sense as it will certainly improve the popularity of the browser provided that developers make use of the new option. (via Sören Hentzschel)
Now You: Which Chrome extension would you like to see ported to Firefox?