Version 100.0a1, first offered to Nightly channel users on March 8, 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.
We now support captions/subtitles display on YouTube, Prime Video, and Netflix videos you watch in Picture-in-Picture. Just turn on the subtitles on the in-page video player, and they will appear in PiP.
Scrollbars on Linux and Windows 11 won't take space by default. On Linux, users can change this on about:preferences. On Windows, we follow the system setting (System Settings > Accessibility > Visual Effects > Always show scrollbars). To change this just on Firefox, use the widget.windows.overlay-scrollbars.enabled pref from about:config.
Users can now choose the preferred color scheme for websites. Theme authors can now make better decisions about which color scheme Firefox uses for menus etc. Web content appearance can now be changed in about:preferences.
Beginning in this release, the Firefox installer for Windows is signed with a SHA-256 digest, rather than SHA-1. Update KB4474419 is required for successful installation on a computer running the Microsoft Windows 7 operating system. For more details about this update, visit the Microsoft Technical Support website.
Some websites might not work correctly in Firefox version 100 due to Firefox's new three-digit version number. You can read about it in our blog post here!