What's new in Firefox Nightly for Developers 4.1.0

Thank you for testing Firefox Preview! This release includes the following changes:
* Login management
* In-App Language Chooser
* Support for Top Sites
* Bypassing Certificate errors
* Fix persistent "Undo closed tab" notification
* Initial extension support featuring uBlock Origin

And many other bug fixes and improvements.

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A more recent upload may be available below!

About Firefox Nightly for Developers 4.1.0

Firefox Nightly for Developers 4.1.0 screenshots (4)

Screenshots from version 154.0a1

Download Firefox Nightly for Developers 4.1.0

This release comes in several variants (we currently have 4). Consult our handy FAQ to see which download is right for you.

Variant
Arch
Version
DPI
4.1.0 APK
20771636
March 19, 2020
armeabi-v7a
Android 5.0+
nodpi
4.1.0 APK
20771637
March 19, 2020
arm64-v8a
Android 5.0+
nodpi
4.1.0 APK
20771638
March 20, 2020
x86
Android 5.0+
nodpi
4.1.0 APK
20771639
March 20, 2020
x86_64
Android 5.0+
nodpi
All Releases

Version:154.0a1

Uploaded:June 18, 2026 at 2:06PM UTC

File size:66.41 MB

Downloads:144

Version:153.0a1

Uploaded:June 15, 2026 at 2:12PM UTC

File size:65.26 MB

Downloads:1,384

Version:152.0a1

Uploaded:May 18, 2026 at 2:18PM UTC

File size:62.75 MB

Downloads:1,312

Version:151.0a1

Uploaded:April 20, 2026 at 1:22PM UTC

File size:59.06 MB

Downloads:1,582

Version:150.0a1

Uploaded:March 23, 2026 at 11:36AM UTC

File size:58.14 MB

Downloads:1,336

Firefox Nightly for Developers 149.0a1

Version:149.0a1

Uploaded:February 23, 2026 at 1:04PM UTC

File size:57.05 MB

Downloads:2,400

Firefox Nightly for Developers 148.0a1

Version:148.0a1

Uploaded:January 12, 2026 at 2:44PM UTC

File size:56.34 MB

Downloads:1,424

Firefox Nightly for Developers 147.0a1

Version:147.0a1

Uploaded:December 8, 2025 at 1:51PM UTC

File size:55.60 MB

Downloads:1,804

Firefox Nightly for Developers 146.0a1

Version:146.0a1

Uploaded:November 10, 2025 at 2:18PM UTC

File size:58.28 MB

Downloads:2,210

Firefox Nightly for Developers 145.0a1

Version:145.0a1

Uploaded:October 13, 2025 at 8:09AM UTC

File size:58.17 MB

Downloads:1,310

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