For some time we’ve heard from add-on developers that our APIs could be better documented and easier to use. In addition, we’ve noticed that many Firefox add-on developers also maintain a Chrome, Safari, or Opera extension with similar functionality. 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.

To this end, we are implementing a new, Blink-compatible API in Firefox called WebExtensions. Extension code written for Chrome, Opera, or, possibly in the future, Microsoft Edge will run in Firefox with few changes as a WebExtension.