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See what landed recently in Firefox Nightly!

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.

152.0a1 Firefox Nightly

April 20, 2026

Version 152.0a1, first offered to Nightly channel users on April 20, 2026

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 Bluesky account, our @FirefoxNightly Mastodon account as well as read our Nightly Blog.

You can interact with other Firefox Nightly users and give your feedback to Mozilla staff in the Nightly Matrix room on chat.mozilla.org.

New

  • Starting with Firefox for Android 150, Nightly users can now choose a custom default location for their downloads.

    Bug 2019009

  • Starting with Firefox 152, Nightly builds have an in-memory cache for the JavaScript compilation result, which is shared across navigation within the same domain, in order to improve the page load performance. The cache works in the same way as the existing in-memory cache for the stylesheets and the images. This can affect how the cached requests/responses are handled in DevTools, WebDriver, and WebExtensions APIs such as webRequest and declarativeNetRequest.

    Bug 2027803

  • Starting with Firefox 151, Firefox for Android nightly builds include settings for enabling fine-grained control of AI features and also allows you to block future AI features.

    Bug 2029260

  • Starting with Firefox 151, you can merge multiple PDFs within the Firefox PDF viewer in Nightly builds.

    Bug 2030178

  • Improved support for more advanced cursor movement commands, including those relating to paragraph boundaries, on macOS.

    Bug 103422

  • Starting with Firefox 152, the address bar in Nightly builds autofills the pages you visit most - including specific pages within a site, not just site homepages - based on your browsing habits, and lets you dismiss suggestions you don’t want.

    Bug 2032547

  • Video controls like play, pause, fullscreen, mute, and loop are now available in the right-click menu, even on sites like Instagram and TikTok where custom video players previously blocked access to them.

    Bug 2035663

  • You can now shush your browser from the address bar by typing "mute" (or "shush" or "sssh") and using the address bar quick action. This will mute all tabs currently playing sound, in all Firefox windows.

    Bug 2019338

Fixed

  • In multiple monitor situations, the About Firefox window now more reliably opens on the display with the most recently-used Firefox window.

    Bug 1868738

  • Fixed a number of text editing commands involving arrow keys in right-to-left languages on macOS.

    Bug 1425483

  • GTK: Fixed the direction of word-based selection commands in RTL text fields.

    Bug 1138419

  • Improved the reliability of saving images when dragging images to the desktop or Finder windows on macOS.

    Bug 643096

Changed

  • Site zooming via keyboard or mouse now supports more and smaller increments.

    Bug 2036853

Developer

  • Developer Information

  • Starting with Firefox 151, the JavaScript Tracer can be enabled from DevTools Settings panel in Nightly builds. This enables tracing all JavaScript function calls. Unlike the performance profiler, this doesn't record a sample; instead, it traces all function calls.

    Bug 2022844

Web Platform

  • Starting with Firefox 150, multiple import maps per document are now supported in Nightly builds, giving web developers more flexibility when structuring and loading modern JavaScript modules. This is considered experimental as we gather feedback before enabling it in regular releases.

    Bug 1916277

    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.

  • Web Notifications can now have action buttons via actions option. Added actions can show up as buttons below notification text, or in "Options" list in case of macOS.

    Bug 1959931

  • The field-sizing property is now available, allowing form controls to adjust in size to fit their contents.

    Bug 2036620

  • Starting with Firefox 152, Nightly builds now support the WebAssembly JS-Promise-Integration proposal, improving the porting of applications to the Web.

    Bug 2015877

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