Download Mozilla Firefox 21.0 Beta

As we are used to from Mozilla, the first beta release of the next version has already appeared shortly after the release of a stable version of the Firefox web browser. Version 21, which should be released on May 14, will include improved Do Not Track options and Firefox will suggest ways to reduce boot time. WebRTC will also become available, which will allow voice and video calls and p2p file exchange, among other things, without the need for separate plugins. Below is the provisionally incomplete overview of the improvements that we can expect in version 21.

New

• Enhanced three-state UI for Do Not Track (DNT)
• Firefox will suggest how to improve your application startup time if needed
• Preliminary implementation of Firefox Health Report (see FAQ)

Changed

• Ability to Restore removed thumbnails on New tab Page
• Add-ons History API removals in Places
• CSS -moz-user-select:none selection changed to improve compatibility with -webkit-user-select:none (bug 816298)
• Graphics-related performance improvements (bug 809821)
• Removed E4X support from SpiderMonkey

Developer

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

HTML5

• Added support for
  element
• Implemented scoped style sheets

Fixed

• Some function keys may not work when pressed (833719)
• Browsing and Download history clearing needs unification to avoid confusion on clearing download history (847627)

Known Issues

• If you try to start Firefox using a locked profile, it will crash (see 573369)
• Download statusbar add-on continues downloading files from Normal Browsing, when switching to Private Browsing (see 853463)

The following downloads are available:
Mozilla Firefox 21.0 beta for Windows (English)
Mozilla Firefox 21.0 beta for Linux (English)
Mozilla Firefox 21.0 beta for OS X (English)
Mozilla Firefox 21.0 Beta for Windows (English)
Mozilla Firefox 21.0 Beta for Linux (English)
Mozilla Firefox 21.0 Beta for OS X (English)
Mozilla Firefox 21.0 beta for Windows (Frisian)
Mozilla Firefox 21.0 beta for Linux (Frisian)
Mozilla Firefox 21.0 beta for OS X (Frisian)