[9] In 2015, a community group formed under the W3C to create a single standard application programming interface (API) for browser extensions.
[10] While this particular work did not reach fruition,[11] every major browser now has the same or very similar API due to the popularity of Google Chrome.
[15] In the same year, Chrome overtook Internet Explorer as the world's most popular browser,[16] and its usage share reached 60% in 2018.
[21] In 2015, Mozilla announced that the long-standing XUL and XPCOM extension capabilities of Firefox would be replaced with a less-permissive API very similar to Chrome's.
[25] Apple was the last major exception to this trend, but support for extensions conforming to the Chrome API was added to Safari for macOS in 2020.
[27] In 2021, these browser vendors formed a new W3C community group, called WebExtensions, to "specify a model, permissions, and a common core of APIs".