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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.

133.0 Firefox Release

November 26, 2024

Version 133.0, first offered to Release channel users on November 26, 2024

New

  • Firefox now has a new anti-tracking feature, Bounce Tracking Protection, which is now available in Enhanced Tracking Protection's "Strict" mode. This feature detects bounce trackers based on their redirect behavior and periodically purges their cookies and site data to block tracking.

  • The sidebar to view tabs from other devices can now be opened via the Tab overview menu.

    screenshot of the Tab Overview menu showing the tabs from other devices menu entry

  • Canvas2D switched from Direct2D to a platform independent acceleration backend on Windows.

Fixed

  • Various security fixes.

  • The “Picture-in-Picture: auto-open on tab switch” feature from Firefox Labs now behaves more reliably across a wider range of sites, automatically opening relevant videos while ignoring others.

Changed

  • When server time is available, the "expire" attribute value is adjusted by adding the difference between the server and local times. If the current time is set in the future, cookies that have not expired according to the server time are considered valid.

Enterprise

Developer

  • Firefox now supports the keepalive option in the Fetch API. This feature allows developers to make HTTP requests that can continue to run even after the page is unloaded, such as during page navigation or closing.

  • Firefox now supports the Permissions API in Worker Context.

  • Firefox now dispatches beforetoggle events just before a dialog opens and toggle events after the dialog closes, matching the behavior of popovers.

  • Methods are now available on UInt8Array to convert to and from Base64 and hexadecimal encodings. This is an implementation of a Stage 3 TC39 proposal, for more details see the proposal text.

  • Added support for image decoding as part of the WebCodecs API. This allows for decoding of images from the main and worker threads.

Community Contributions

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