Version 91.0a1, first offered to Nightly channel users on May 31, 2021
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.
Firefox now supports logging into Microsoft, work, and school accounts using Windows single sign-on. Learn more