I would argue that Firefox’s selection of add-ons is the best of any web browser, but many would understandably disagree. Although developing Firefox add-ons allows you to access more of the browser’s underlying features, it’s also a more complex process than developing similar add-ons for Blink-based browsers like Chrome and Opera. That’s no longer going to be the case, however, as Mozilla will be adopting a new extension API that will make it much easier for developers to bring their extensions over from Chrome to Firefox. 

Mozilla today announced major changes to how Firefox will implement add-ons going forward. The most important of these is the adoption of a new extension API that will be largely compatible with the one currently in use by Blink-based browsers like Chrome and Opera. This so-called WebExtensions API will ensure that developers will only have to make a few small changes to their code for their add-on to run on Firefox. “We would like add-on development to be more like Web development: the same code should run in multiple browsers according to behavior set by standards, with comprehensive documentation available from multiple vendors,” Mozilla’s Kev Needham writes in today’s announcement. Writing extensions for Firefox was always a bit more complex than writing something with the same functionality for Chrome. That’s partly due to Firefox’s use of technologies like XPCOM and XUL (for building user interfaces). These allowed the browser to be mostly written in JavaScript and ensured that extensions developers got access to a lot of Firefox’s underlying features, but also added complexity.