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.

Firefox Nightly

February 7, 2022

Version 99.0a1, first offered to Nightly channel users on February 7, 2022

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.

Warning: 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.


  • You can now toggle Narrate in ReaderMode with the keyboard shortcut "n".

    Bug 1749038
  • Page navigation (back or forward) can now be triggered using a horizontal two-finger swipe gesture on Windows touchpads.

    <!--- Nightly Only ---!>

    Bug 1753885
  • Linux: GTK overlay scrollbars are now enabled on Nightly and early betas

    Bug 1147847
  • Added support for search with or without diacritics in the PDF viewer

    Bug 1753509


  • Developer Information
  • Nightly-only: The New Request side panel in the DevTools Network tool has been refactored and its usability improved. Developers may use it to send (and resend) synthetic HTTP network requests without having to change their code and refresh their page. It's also useful for building and testing REST APIs.

    Bug 1745415

Community Contributions

  • With Firefox version 100 rapidly approaching, you can help test websites' compatibility with three-digit version numbers by enabling the new Firefox 100 User-Agent String option in the Experimental section of Settings (about:preferences#experimental). If you find a website that is broken with Firefox version 100, please file a bug report on

    Bug 1748798
All Firefox Nightly downloads