Changes

=New Standard in A Cross-Browser API for Developing Add-on Developmentons=The technology for developing add-ons is in transition to [https://developer.mozilla.org/en-US/Add-ons/WebExtensions WebExtensionsAPIs] are now the standard . These APIs let you create and maintain one codebase that works across multiple browsers, without having to update it for add-on development in every Firefox. It will be the only type of add-on supported in Firefox by the end of 2017 with the release of [https://wiki.mozilla.org/RapidRelease/Calendar Firefox 57].

With the release of [https://wiki.mozilla.org/RapidRelease/Calendar Firefox 57] in November, only add-ons built with WebExtensions APIs will be supported. This page contains timelines, tutorials, and other resources to help you port your legacy add-on to use WebExtensionsAPIs. If you're looking for resources on creating a new add-on, please head over to [https://developer.mozilla.org/en-US/Add-ons/WebExtensions MDN].

*June 14, 2017: [https://blog.mozilla.org/addons/2017/06/14/webextensions-firefox-55/ WebExtensions in Firefox 55]*May 16, 2017: [https://blog.mozilla.org/addons/2017/05/16/compatibility-firefox-55/ Add-on Compatibility for Firefox 55]*May 10, 2017: [https://blog.mozilla.org/addons/2017/05/10/incompatible-change-sessions-restore-api-firefox-54/ Incompatible change to sessions.restore API in Firefox 54]