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

December 10, 2018

Version 66.0a1, first offered to Nightly channel users on December 10, 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.


  • Support for the AV1 video codec is now activated on Windows

    Bug 1452146
  • Added the ability to search through your open tabs from the tab overflow menu

    Bug 1516083
  • Web Extensions keyboard shortcuts can now be managed or overridden from about:addons

    Bug 1303384
  • Added experimental Touch Bar support on macOS

    Bug 1313429
  • The home page in a Private Browsing windows now includes a search field which uses your default search engine

    Bug 1508364


  • On Linux the Title Bar is now merged with the Tab Bar by default. This new behavior can be modified via the Customize… item in the main menu.

    Bug 1283299
All Firefox Nightly downloads