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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.

136.0 Firefox Release

March 4, 2025

Version 136.0, first offered to Release channel users on March 4, 2025

New

  • You can now enable the updated Firefox sidebar in Settings > General > Browser Layout to quickly access multiple tools in one click, without leaving your main view. Sidebar tools include an AI chatbot of your choice, bookmarks, history, and tabs from devices you sync with your Mozilla account.

    screenshot Firefox browser with the sidebar enabled and the customize sidebar settings displaying the various settings

  • Keep a lot of tabs open? Try our new vertical tabs layout to quickly scan your list of tabs. With vertical tabs, your open and pinned tabs appear in the sidebar instead of along the top of the browser. To turn on vertical tabs, right-click on the toolbar near the top of the browser and select Turn on Vertical Tabs. If you’ve enabled the updated sidebar, you can also go to Customize sidebar and check Vertical tabs. Early testers report feeling more organized after using vertical tabs for a few days.

    screenshot of the firefox browser with vertical tabs enabled

  • The Clear browsing data and cookies dialog now allows clearing saved form info separately from browsing history.

    screenshot of the Clear browsing data and cookies dialog. Demonstrating the separate options for form data and browsing history

  • Smartblock Embeds allows users to selectively unblock certain social media embeds that are blocked in ETP Strict and Private Browsing modes. Currently, support is limited to a few embed types, with more to be added in future updates.

  • Firefox now upgrades page loads to HTTPS by default and gracefully falls back to HTTP if the secure connection fails. This behavior is known as HTTPS-First.

  • On macOS, some background tabs will be moved to lower power cores, reducing energy usage.

  • Hardware-accelerated playback of HEVC video content is now supported on macOS.

  • Hardware video decoding is now enabled for AMD GPUs on Linux.

  • On Linux, Firefox is now available on ARM64 (AArch64), with installation options via APT and tarballs. Flatpak support is coming soon.

  • The Weather forecast on the New Tab page is expanding to additional regions, including Mexico, Brazil, Argentina, and Chile, as part of an ongoing regional rollout.

    This feature is part of a progressive roll out.

    What is a progressive roll out?

    Certain new Firefox features are released gradually. This means some users will see the feature before everyone does. This approach helps to get early feedback to catch bugs and improve behavior quickly, meaning more Firefox users overall have a better experience.

  • Address autofill enabled for users in the United Kingdom.

    This feature is part of a progressive roll out.

    What is a progressive roll out?

    Certain new Firefox features are released gradually. This means some users will see the feature before everyone does. This approach helps to get early feedback to catch bugs and improve behavior quickly, meaning more Firefox users overall have a better experience.

Fixed

  • Firefox will now prefer the PNG format when copying images out of Firefox, allowing the preservation of transparency.

  • Various security fixes.

Changed

  • For New Tab stories, the Save to Pocket action was moved from a button to the context menu along with other actions, such as Bookmark.

  • The macOS DMG installer packages now use LZMA for compression, reducing download size and installation time.

  • Due to recent changes in macOS Sequoia, the shortcut for completing search strings to .com addresses has been changed from Ctrl+Enter to Cmd+Enter.

Enterprise

Developer

  • Developer Information

  • The Developer Tools debugger editor now uses Codemirror 6, which improves performance.

Web Platform

  • Added support for the Intl.DurationFormat object; this enables language-sensitive duration formatting.

  • Added support for the CSS :open pseudo-class for styling elements that can be toggled “open” to display more content.

  • Added support for the :has-slotted pseudo-class, allowing authors to style the contents of a <slot> element when it is not empty or not using the default value.

  • Added support for the CookieStore API, an asynchronous cookie API for scripts running in HTML documents and service workers.

  • Added support for ARIA elements reflection.

  • Firefox now sends a referrer from meta refreshes and Refresh headers.

  • Added support for sending and receiving the AV1 video codec over WebRTC. Both singlecast and simulcast are supported for sending.

  • Added support for sending multiple simultaneous versions of the same source over WebRTC, commonly called simulcast, with the H264 video codec. H264 is the second video codec after VP8 to be supported for sending simulcast.

  • The value plaintext-only can now be specified for the contenteditable attribute, making the raw text of an element editable but without supporting rich text formatting.

  • Added support for the text replacement feature in an input field on macOS. Web content can enable/disable this using the HTML autocorrect attribute.

Community Contributions

  • With the release of Firefox 136, we are pleased to welcome the developers who contributed their first code change to Firefox in this release, 10 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:

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