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 complete list of changes in this release.


Firefox Release

March 18, 2014

Version 28.0, first offered to Release channel users on March 18, 2014

Thanks to our contributors linkCheck out "What’s New" and "Known Issues" for this version of Firefox below. As always, you’re encouraged to tell us what you think, or file a bug in Bugzilla.

We'd also like extend a special thank you to all of the new Mozillians who contributed to Firefox 28!!


  • VP9 video decoding implemented

  • Support for Opus in WebM

  • Horizontal HTML5 audio/video volume control

  • Mac OS X: Notification Center support for web notifications



  • Now that spdy/3 is implemented support for spdy/2 has been removed and servers without spdy/3 will negotiate to http/1 without any penalty


  • Support for multi-line flexbox in layout

  • Background thread hang reporting

  • Support for MathML 2.0 'mathvariant' attribute

Developer Information


  • Text Rendering Issues on Windows 7 with Platform Update KB2670838 (MSIE 10 Prerequisite) or on Windows 8.1 has a workaround (see 812695)

  • Echo cancellation on fails (974537)