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What's new in Firefox Nightly for Developers 139.0a1
From version 5.2.0:
* Sort Logins
* Streamline Bookmarks/History access
* Improved QR code scanning
* Stability and bugfixes
About Firefox Nightly for Developers 139.0a1
Warning: Nightly is an unstable testing and development platform. By default, Firefox Nightly automatically sends data to Mozilla — and sometimes our partners — to help us handle problems and try ideas. Learn what is shared: www.mozilla.org/en-US/privacy/firefox/#pre-release
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Firefox Nightly gets updated every day and is designed to showcase the more experimental builds of Firefox. The Nightly channel allows users to experience the newest Firefox innovations in an unstable environment and provide feedback on features and performance to help determine what makes the final release.
Found a bug? Report it at: bugzilla.mozilla.org/enter_bug.cgi?product=Fenix
Want to know more about the permissions Firefox requests?: mzl.la/Permissions
See our list of supported devices and latest minimum system requirements at: www.mozilla.org/firefox/mobile/platforms/
Mozilla marketing: In order to understand the performance of certain Mozilla marketing campaigns, Firefox sends data, including a Google advertising ID, IP address, timestamp, country, language/locale, operating system, app version, to our third party vendor. Learn more by reading our Privacy Notice here: www.mozilla.org/privacy/firefox/
Take a browse on the wild side. Be among the first to explore future releases.
Download Firefox Nightly for Developers 139.0a1
This release comes in several variants (we currently have 27). Consult our handy FAQ to see which download is right for you.
Version:157.0a1
Uploaded:September 9, 2026 at 2:21AM UTC
File size:48.14 MB
Downloads:409
Version:156.0a1
Uploaded:August 28, 2026 at 7:42PM UTC
File size:47.84 MB
Downloads:376
Version:155.0a1
Uploaded:August 13, 2026 at 1:25PM UTC
File size:48.15 MB
Downloads:852
Version:154.0a1
Uploaded:July 20, 2026 at 5:02PM UTC
File size:66.41 MB
Downloads:1,547
Version:153.0a1
Uploaded:June 15, 2026 at 2:12PM UTC
File size:65.26 MB
Downloads:1,477
Version:152.0a1
Uploaded:May 18, 2026 at 2:18PM UTC
File size:62.75 MB
Downloads:1,361
Version:151.0a1
Uploaded:April 20, 2026 at 1:22PM UTC
File size:59.06 MB
Downloads:1,601
Version:150.0a1
Uploaded:March 23, 2026 at 11:36AM UTC
File size:58.14 MB
Downloads:1,410
Version:149.0a1
Uploaded:February 23, 2026 at 1:04PM UTC
File size:57.05 MB
Downloads:2,539
Version:148.0a1
Uploaded:January 12, 2026 at 2:44PM UTC
File size:56.34 MB
Downloads:1,501
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