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Firefox Developer Edition icon

Firefox Developer Edition

149.0b3
Dev Onboard
5 1 reviews
12.5 k downloads
security security

A version of the popular browser especially for developers

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Álvaro Toledo icon
Reviewed by
Álvaro Toledo
Chief Content Officer
Álvaro Toledo is part of Uptodown's in-house Editorial Team. Translated by Uptodown Localization Team

The Mozilla Foundation has an alternative to its stable client where they publish test versions of its browser that will be officially distributed in the future. Firefox Developer Edition has now replaced the Aurora channel to offer an updated version of the browser each month and a half, long before its launch on the standard channel, and also has some extra functionalities focused on web development.

This version includes several tools to create, edit, and test projects on several devices and browsers, with all the new features grouped into a drop-down menu in the toolbar. It includes the WebID system, a development kit to create webpages and applications for Firefox OS, and also has an extension to view and edit projects on other devices like smartphones and tablets, and another to check pages on other browsers like Chrome or Safari.

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Its other features include options to inspect the page's source code and modify the HTML and CSS directly from the browser while viewing the changes in real time. It also offers debugging and performance-analysis options that allow, for example, checking the status of the network when sending online requests, or viewing a change log with all the interactions you do to a page.

For the standard user, the only difference from the original Firefox is a darker theme and the aforementioned features that aren't yet included on the stable channel, making this version ideal for developers as well as those who want to be privy to the latest developments on their favorite browser.

Information about Firefox Developer Edition 149.0b3

Basic information

Developer Mozilla
License Free
Category Navigation
Rating Not specified
Languages English
1 more

Security and privacy

Required permissions Not applicable
Advertising Not specified
See security and antivirus report
Why is this app published on Uptodown? (More information)

Download info

Downloads 12,458
Date Mar 4, 2026
File type DMG
Size 160.43 MB
SHA256 32a6a23ca4f6ac3e04fcb89e326ae351c1a0cb410e36df6a62a8165c28661a68
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Older versions

See more
dmg 148.0b13 Feb 11, 2026
dmg 148.0b10 Feb 4, 2026
dmg 148.0b4 Jan 21, 2026
dmg 146.0b7 Nov 26, 2025
dmg 146.0b4 Nov 19, 2025
dmg 146.0b1 Nov 13, 2025
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