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 Developer Edition

January 27, 2017

Version 53.0a2, first offered to Firefox Developer Edition channel users on January 27, 2017

For more information about Developer Edition please see this MDN article.


  • Lightweight themes are now applied in private browsing windows

  • Reader Mode now displays estimated reading time for the page

  • New installs on Win7+ 64 bit OS now default to 64 bit Firefox

  • On qualified Windows systems, a new 'compositor process' mitigates the risk of device driver related browser crashes

  • Two new 'compact' themes available in Firefox, dark and light, based on the Firefox Developer Edition theme


  • Windows XP and Vista are no longer supported. XP and Vista users running Firefox 52 will continue to receive security updates for another year.

  • 32-bit Mac OS X is no longer supported. Firefox is now a 64-bit only Mac OS X application

  • Ended Firefox Linux support for processors older than Pentium 4 and AMD Opteron

  • Refresh of the media controls user interface

  • Shortened titles on tabs are faded out instead of using ellipsis for improved readability

  • Media playback on new tabs is blocked until the tab is visible

  • Process separation (e10s) now supported on Windows 10 touch screen devices and systems with accessibility tools installed

  • Select menus offer an inline search when the menus are over 40 items


Developer Information