Firefox Developer Edition

June 10, 2016

Version 49.0a2, first offered to Firefox Developer Edition channel users on June 10, 2016

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


  • Updated Firefox Login Manager to allow HTTPS pages to use saved HTTP logins. It’s one more way Firefox is supporting Let’s Encrypt and helping users transition to a more secure web.

  • Added features to Reader Mode that make it easier on the eyes and the ears

    • Controls that allow users to adjust the width and line spacing of
    • Narrate, which reads the content of a page out loud
  • Improved video performance for users on systems that support SSSE3 without hardware acceleration

  • HTML5 audio and video improvements

    • Files can now be looped through the built-in controls in the context menu
    • Play audio and video at 1.25× speed through the context menu
  • Enhancements for Mac users

    • Improved performance on OS X systems without hardware acceleration
    • Improved appearance of anti-aliased OS X fonts
  • Reader Mode can now read articles out loud

  • Improved appearance of anti-aliased OS X fonts


  • Fixed an issue that prevented users from updating Firefox for Mac unless they originally installed Firefox. Now, those users as well as any user with administrative credentials can update Firefox.



All Firefox Developer Edition downloads