Firefox Developer Edition 156.0のダウンロード

Version 156.0beta, first offered to Beta channel users on August 31, 2026
Firefox Beta gets updated 3 times a week and as a consequence, the release notes for the Beta 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 via the Firefox Trains website or our @FirefoxBeta Bluesky account.

New
- macOS users can now configure Firefox to launch automatically at startup via Settings.
- Improved memory and CPU usage when Firefox displays large JPEG images scaled down to fit a page.
- Localized Wikipedia and occasional sponsored suggestions in the address bar now available in France, Germany, and Italy (can be disabled in Firefox Suggest settings).
- Firefox for Android media notifications now include previous/next buttons and timeline seeking controls.
- Firefox for Android sharing now uses native Android share sheet on Android 14+, with options like Send tab to device and Scan QR code.

Fixed
- Windows ARM64 devices: WebRTC video calls may now use hardware H264 decoding.
- Fixed dragging an inline image to a new position in a rich-text editor replacing it with a long line of text instead of moving it.
- All devices: WebRTC video calls may now use hardware AV1 decoding.
- Fixed high-sample-rate FLAC audio in MP4 failing to play on sites such as Bilibili.
- Fixed find bar becoming permanently unavailable after reversing panes in Split View.
- Windows: fixed Firefox blocking auto-hiding taskbars.
- Firefox for Android: fixed crashes when selecting files from certain Android file providers.
- Fixed subtitles not appearing in Picture-in-Picture after being enabled post-launch.
- Firefox for Android: fixed date picker allowing dates before minimum when maximum was specified.

Changed
- Firefox's built-in PDF viewer now starts up to 45% faster.

Enterprise
- FirefoxHome policy now includes Widgets option for controlling new tab productivity widgets.
- SitePolicies policy now supports DisableServiceWorkers for blocking service worker registration.
- Windows installer now resolves /INI= paths relative to installer location.
- Fixed DontCheckDefaultBrowser and DefaultBrowserSettingEnabled policies being ignored on new profiles.

Web Platform
- text-box-trim now uses font metrics of ::first-line pseudo-elements when applicable.