Firefox Developer Edition 48.0

Firefox Developer Edition is a version of Mozilla product created specifically for software developers. It has several new features and unique functionality. This version of the browser can actually operate independently of standard Firefox and family browsers like Safari. It borrows the default colors and interface elements from the developer tool set which makes the interface itself easy to use and navigate if you have any experience in development of products in this line.

Some of the new tools, like the Valence add-on, give you access to Firefox developer tools for other browsers. Other notable features include things like Responsive Design View, which lets users change screen sizes in real-time without adjusting size of their browser window. Then, there's the style editor, a tool that lets you edit CSS page styles, to create your own variations and apply existing CSS style sheets to other pages.

Firefox Developer Edition is an all-in-one toolbox for people into browser development. It has all the basic tools and some of the more advanced features one would expect from a software bundle like this.

v48.0 [Apr 27, 2016]
New
Geometry editor to move absolute and fixed positioned elements
Tree map view in memory tool
Cloning of MediaStream and MediaStreamTrack is now supported. (MediaStreamGraph & WebRTC)
ICE Restart & Update is supported (WebRTC)
Firebug theme available for Developer Tools
Reload add-ons from about:debugging for easy add-on development
Expand network requests from the console panel to view request details in line
Visualize animations running on ::before and ::after pseudo-elements using animation inspector
Use Tab and Shift F10 to customize Firefox using a keyboard
Enhanced protection against malware downloads
Skia enabled by default on GNU/Linux
Fixed
Improved step debugging on last line of functions
Changed
Ending support for Firefox on OS X 10.6, 10.7, and 10.8
Fixed Jabra headset and Logitech C920 webcam audio issue; users heard a frequency distorted (i.e. "Mickey Mouse") voice (WebRTC)
Delay-agnostic AEC should now be working and enabled on all platforms (WebRTC)
Full duplex for Linux and Mac is pref'd on (WebRTC)
Deprecated Error Console, use Browser Console instead
Removed integration with Windows Remote Access Service modem Autodial
The URL bar result panel has a new design and shows more results
Developer
Added support for Element.animate()
Added support for Element.animate()
Added vertical text layout support with the "text-combine-upright: all" CSS property
Implemented Document.scrollingElement to tell which element's scroll attributes reflect the viewport scroll state
WebExtensions background content scripts and background pages can now be debugged
WebExtensions have Content Security Policy (CSP) enforced
Web Crypto API is now available in Workers