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".
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.
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 webcompat.com.