See what’s new in Firefox!

Release Notes tell you what’s new in Firefox. As always, we welcome your feedback. You can also file a bug in Bugzilla or see the system requirements of this release.


Firefox for Android Release

May 14, 2013

Version 21.0, first offered to Release channel users on May 14, 2013




  • Ability to restore removed thumbnails on New tab Page

  • Add-ons History API removals in Places

  • XBL Scopes Enabled (bugs 834697)

  • CSS -moz-user-select:none selection changed to improve compatibility with -webkit-user-select:none (bug 816298)

  • Removed E4X support from Spidermonkey

  • Graphics related performance improvements (bug 809821)


  • Implemented Remote Profiling

  • Integrated, Add-on SDK loader and API libraries into Firefox

Developer Information

Web Platform

  • Browsing and Download history clearing needs unification to avoid confusion on clearing download history

  • Some function keys may not work when pressed


  • If you try to start Firefox using a locked profile, it will crash (see 573369)