Download Firefox

Firefox is no longer supported on Windows 8.1 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox is no longer supported on macOS 10.14 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox Privacy Notice

Firefox Nightly
Release Notes

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.

63.0a1 Firefox Nightly

June 25, 2018

Version 63.0a1, first offered to Nightly channel users on June 25, 2018

Firefox Nightly gets updated every day and as a consequence, the release notes for the Nightly channel are updated continuously to reflect features that have reached sufficient maturity to benefit from community feedback and bug reports. Features listed here may or may not make a final release of Firefox.

In addition to these release notes, you can follow ongoing development on our @FirefoxNightly Twitter account as well as read our Nightly Blog.


  • WebExtensions now run in their own process on Linux

    Bug 1357487
  • Firefox now warns about having multiple windows and tabs open when quitting from the main menu. The Save and Quit feature has been removed. You can restore your session by ticking the box for Restore previous session in the General → Startup options or by using Restore Previous Session in the main menu.

    Bug 1438499
  • Improved page load performance by blocking cross-site tracking

    Bug 1480443
  • On macOS, WebGL power preferences allow non-performance-critical applications and applets to request the low-power GPU instead of the high-power GPU in multi-GPU systems

    Bug 1349799
  • Multiple tabs can now be selected using Ctrl/Cmd and Shift. These selected tabs can be muted, moved, bookmarked, pinned, and more simply and quickly.

    Bug 1474704
  • Improved Windows 10 integration: your Firefox theme now matches your OS Dark / Light mode

    Bug 1368808
  • Firefox by default now prompts for permission before allowing pages to automatically play media with sound

    Bug 1476853
  • Faster tab switching in the majority of cases for our macOS users

    Bug 1481519
  • Improved the reactivity of Firefox on macOS

    Bug 1265824
  • TLS certificates issued by Symantec are no longer trusted by Firefox Nightly. Website operators are strongly encouraged to replace any remaining Symantec TLS certificates before Firefox 63 final release on October 23.

    Bug 1460062


  • In the Library, the Open in Sidebar feature for individual bookmarks was removed

    Bug 1452645
  • The option to Never check for updates was removed from about:preferences. You can use the DisableAppUpdate enterprise policy as a substitute.

    Bug 1420514
  • The Ctrl+Tab shortcut now displays thumbnail previews of your tabs and cycles through tabs in recently used order. This new default behavior is activated only in new profiles and can be changed in preferences.

    Bug 1473595
  • The build infrastructure of Firefox on Windows moved to the Clang tool chain, bringing important performance gains

    Bug 1443590

Get the most recent version

All Firefox Nightly downloads