Mozilla Firefox 146

Version 146.0, first offered to Release channel users on December 9, 2025

New

• Windows 10 users can now automatically protect their passwords, bookmarks, and more by turning on backup in Firefox. Your browsing data is saved daily on your device and can be encrypted with a password. When you set up a fresh install of Firefox on any operating system for a new device or your current one, you can restore from this backup and pick up right where you left off. This feature is currently available on Windows devices and will be coming to other operating systems soon.

  This feature is part of a progressive roll out.

• MacOS users now have a dedicated GPU process by default. This includes WebGPU, WebGL, and Firefox’s own WebRender. With this feature enabled, fatal errors in graphics code will no longer crash the browser, and will instead transparently restart the GPU process.

• Firefox Labs is now available to all desktop users, regardless of whether they choose to participate in studies or submit telemetry. This means more experimental features are now available to more people.

• Users can now skip the results page and see direct results as they type in the search bar for faster, simpler browsing.

  This feature is part of a progressive roll out.

• There is a New Tab Weather opt-in workflow available for users in the EU and some other countries, where they can choose whether to enable location detection or manually search for a location.

  This feature is part of a progressive roll out.

• Firefox now natively supports fractional scaled displays on Linux (Wayland), making rendering more effective.

• For users of the English-language versions of Firefox in France, Germany, and Italy, the address bar now shows English-language suggestions for holidays and other important dates.

Fixed

• When the timepicker is enabled for <input type="time"> and <input type="datetime-local">, it now provides full keyboard and assistive technology support. This update also improves the behavior of the time spin buttons for users who prefer reduced motion. The Firefox Accessibility team hopes that making the built-in timepicker accessible will encourage wider adoption of browser-provided time and date inputs across the web, reducing the need for custom controls, and improving accessibility for all users.

• Various security fixes.

Changed

• The Colors dialog in Settings now uses clearer color picker controls that keep each color sample next to its label. It makes it easier to understand and adjust text, background, and link colors when using a forced colors palette to customize the default text, link, and page background colors, especially with or without screen magnifiers.

• Firefox removed support for Direct2D on Windows. If you still require Direct2D support, please use ESR 140.0 or higher.

Enterprise

• You can find information about policy updates and enterprise specific bug fixes in the Firefox for Enterprise 146 Release Notes.

Developer

• Developer Information

• Firefox now supports ML-KEM for WebRTC, by sending a post-quantum (PQ) key share during the DTLS 1.3 handshake. ML-KEM is the next-generation public-key cryptosystem that is believed to be secure against attackers with large quantum computers.

• Firefox now supports compressed elliptic curve points in WebCrypto. These reduce the size of public keys by nearly half, saving bandwidth and storage, while still allowing the full point to be reconstructed mathematically.

• The Skia graphics library has been updated to improve rendering performance and compatibility.

• Unused CSS custom properties are now hidden by default in the Rule view of the Inspector. This not only reduces clutter, but in some cases also speeds up the rendering of the inspector panel.

Web Platform

• The @scope rule is now supported, allowing authors to restrict styling to a subtree of the DOM. This avoids having to write overly-specific selectors.

• Firefox now supports the contrast-color() CSS function that takes a color value and returns a contrasting color. Note that the specification currently restricts the contrasting color to black or white. This limitation is expected to be removed in the future. (Learn more)

• Introduced the text-decoration-inset property, which allows authors to adjust the start and end points of line decorations.

• Firefox now supports the legacy -webkit-fill-available keyword as a value for the CSS width and height properties. This improves rendering of content on websites that use this value. This keyword is an alias for the recently standardized stretch keyword, which is not yet enabled in Firefox.

Unresolved

• On Windows, clicking tabs may not work at the very top of the screen when Firefox is maximized on a second monitor. We’re working to fix this in a future release. (Fixed in 147.0)

Community Contributions

• With the release of Firefox 146, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 16 of whom were brand new volunteers! Please join us in thanking each of these diligent and enthusiastic individuals, and take a look at their contributions:

  • Alex Johnson: 1924339
  • Apurva: 1973318
  • Cornelius Emase: 1913086, 1977921, 1996578, 1996859, 1998012
  • Ethan Gallucci: 1991983
  • gopi: 1940198
  • Jeffrey Houghton: 1900302
  • Julian: 1945449
  • Leonardo Paffi: 1996678
  • Loago Zambe: 1975592
  • Meg Ford: 1898383, 1997187
  • Mingyuan Zhao [:MagentaManifold]: 1995168
  • Pavel Kireev: 400264, 1852625, 1975612, 1986459, 1988355, 1998237
  • PhuongNam: 1968398
  • Simon Knott: 1993703
  • Thomas J Faughnan Jr: 1994098
  • zzjas98: 1997216