See what’s new in Firefox!

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.

139.0 Firefox Release

May 27, 2025

Version 139.0, first offered to Release channel users on May 27, 2025

New

  • By popular request, Full-Page Translations are now available within Firefox extension pages that start with the moz-extension:// URL scheme.

    Screenshot of Firefox Relay extension page translated from English to German

  • The New Tab custom wallpaper (and colors) option is now available! Your own image can be uploaded as your New Tab wallpaper or any custom color can be selected - from the brightest pink to dark gray. This feature will be rolling out gradually to new users and can also be enabled immediately via Firefox Labs. Additionally, new Wallpaper images and a new Celestial category have also been added.

    Screenshot showing the new custom wallpaper upload optionScreenshot showing the color chooser

  • Link Previews is currently available as an experimental feature which can be enabled via Firefox Labs in the Firefox settings. After enabling, use the Alt+Shift keyboard shortcut when hovering over a link to see the previews in action!

    Screenshot showing a preview pane for a hovered link

Fixed

  • PNG images with transparency now keep their transparency when pasted into Firefox.

  • The upload performance of HTTP/3 has been significantly improved, particularly on resumed connections (QUIC 0-RTT) and high-bandwidth and high-delay connections.

  • Various security fixes.

Changed

  • Due to recent changes in how Chrome encrypts user data on Windows, the Firefox migration wizard can no longer directly import payment methods or passwords from Chrome. However, users can still export passwords from Chrome to a CSV file and then import them into Firefox using the migration wizard or the password manager.

  • The Review Checker feature is shutting down and will no longer be available after June 10, 2025.

Enterprise

Developer

  • Developer Information

  • Based on user requests from both Mozilla Connect and Stack Overflow, the filter setting in the Network panel is now preserved across DevTools Toolbox sessions.

  • The Debugger's directory root is now scoped to the specific domain where it was set, which aligns with typical usage and avoids applying it across unrelated domains. This builds on previous improvements such as a redesigned UI and easier removal of the root setting. Setting a directory root updates the Source List to show only the selected directory and its children. Learn more

  • The appearance of the paused line in the Debugger has been refined for better visibility, especially in high contrast mode.

Web Platform

  • The Temporal proposal, a better version of Date, is now enabled by default in Firefox.

  • Timer throttling for Workers is now supported.

  • Closed <details> elements are now searchable and can be automatically expanded if found via find-in-page.

  • Firefox now supports the hidden=until-found attribute, allowing content to be found via find-in-page when it's otherwise hidden by default.

  • window.getSelection().toString() now correctly returns the text serialization when text is selected in a text control, improving cross-browser interoperability on some sites.

  • Added support for the WebAuthn largeBlob extension.

  • Added support for requestClose() to HTMLDialogElement.

  • The built-in editor for contenteditable and designMode now handles collapsible white-space(s) before block boundaries and white-space sequences between visible content more consistently with Chrome. As a result, Gecko no longer inserts a padding <br> element after white-space before a block boundary, aligning behavior with other browsers.

Community Contributions

Get the most recent version

All Firefox downloads