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.

144.0a1 Firefox Nightly

August 18, 2025

Version 144.0a1, first offered to Nightly channel users on August 18, 2025

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 142, Nightly builds support creating URLs using Text Fragments. You can generate such a URL by selecting a snippet of text on a page and choosing Copy Link to Highlight from the context menu.

    Bug 1970641

  • Starting with Firefox 143, Firefox Nightly now blocks local network requests by default and only allows them if the user grants access through a permission prompt, strengthening protection against attacks targeting local network services.

    Bug 1972350

  • You can now close a Picture-in-Picture window without pausing the video. Press Shift + Click on the close button or use Shift + Esc to exit while keeping playback uninterrupted.

    Bug 1982974

  • Logins in the Firefox Password Manager are now encrypted using a more modern encryption scheme, switching from 3DES-CBC to AES-256-CBC. This change only affects the local encryption of logins on the disk; logins synced through Firefox Sync are end-to-end encrypted independently and have already been using a strong encryption scheme (AES-256-GCM) previously.

    Bug 1974184

Changed

  • On Windows, when opening a link from another application, Firefox will only use a window on the current virtual desktop or open a new window if needed.

    Bug 1423768

Developer

Web Platform

  • Starting with Firefox 142, Nightly builds now support the Integrity-Policy header allowing websites to ensure that all of their scripts are protected with integrity data. It is currently limited to scripts but will be expanded in the future to provide full web application integrity.

    Bug 1976656

  • Firefox now supports the Element.moveBefore API.

    Bug 1983688

  • Firefox now supports math-shift compact.

    Bug 1923569

  • Firefox now supports the WebGPU GPUDevice.importExternalTexture API on Windows.

    Bug 1983594

  • Firefox now supports PerformanceEventTiming.interactionId, allowing developers to group related input events. This enables support for the Interaction to Next Paint (INP) responsiveness metric.

    Bug 1956809

  • Firefox now supports the command and commandfor attributes.

    Bug 1983523

  • Starting with Firefox 144, when linear gradient is rendered using hardware WebRender, dithering is now applied in Firefox Nightly.

  • Firefox now supports the View Transition API. The View Transition API provides a mechanism for easily creating animated transitions between different website views.

    Bug 1985809

  • The resizeMode getUserMedia constraint is now available, allowing developers to crop and downscale video captured from a camera to any resolution they choose.

    Bug 1286945

  • Starting with Firefox 144, layer compositor is enabled for WebRender on Windows in Firefox Nightly.

    Bug 1945683

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