Firefox Developer Edition

Welcome to your new favorite browser. Get the latest features, fast performance, and the development tools you need to build for the open web.

Firefox Developer Edition — English (US)

Your system may not meet the requirements for Firefox, but you can try one of these versions:

Firefox Developer Edition — English (US)

Firefox Developer Edition is no longer supported on Windows 8.1 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Download Firefox ESR 64-bit

Download Firefox ESR 32-bit

Download a different build

Firefox Developer Edition is no longer supported on macOS 10.14 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Download Firefox ESR

Firefox Privacy Notice

Using Debian, Ubuntu or any Debian-based distribution?
You can set up our APT repository instead.

Firefox Developer Edition automatically sends feedback to Mozilla. Learn more

Firefox Developer Edition

The browser made for developers

All the latest developer tools in beta in addition to features like the Multi-line Console Editor and WebSocket Inspector.

A separate profile and path so you can easily run it alongside Release or Beta Firefox.

Preferences tailored for web developers: Browser and remote debugging are enabled by default, as are the dark theme and developer toolbar button.

New Tools

Inactive CSS

Firefox DevTools now grays out CSS declarations that don’t have an effect on the page. When you hover over the info icon, you’ll see a useful message about why the CSS is not being applied, including a hint about how to fix the problem.

New Tools

Firefox DevTools

The new Firefox DevTools are powerful, flexible, and best of all, hackable. This includes a best-in-class JavaScript debugger, which can target multiple browsers and is built in React and Redux.

Innovative Features

Master CSS Grid

Firefox is the only browser with tools built specifically for building and designing with CSS Grid. These tools allow you to visualize the grid, display associated area names, preview transformations on the grid and much more.

Faster Information

Fonts Panel

The new fonts panel in Firefox DevTools gives developers quick access to all of the information they need about the fonts being used in an element. It also includes valuable information such as the font source, weight, style and more.

Design. Code. Test. Refine.

Build and Perfect your sites
with Firefox DevTools

Inspector

Inspect and refine code to build pixel-perfect layouts.

Learn more about Page Inspector

Console

Track CSS, JavaScript, security and network issues.

Learn more about Web Console

Debugger

Powerful JavaScript debugger with support for your framework.

Learn more about JavaScript Debugger

Network

Monitor network requests that can slow or block your site.

Learn more about Network Monitor

Storage panel

Add, modify and remove cache, cookies, databases and session data.

Learn more about Storage Panel

Responsive Design Mode

Test sites on emulated devices in your browser.

Learn more about Responsive Design View

Visual Editing

Fine-tune animations, alignment and padding.

Learn more about Visual Editing

Performance

Unblock bottlenecks, streamline processes, optimize assets.

Learn more about Performance Tools

Memory

Find memory leaks and make your application zippy.

Learn more about Memory Tools

Style Editor

Edit and manage all your CSS stylesheets in your browser.

Learn more about Style Editor

Get the most out of Firefox Developer Edition

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Feedback makes us better. Tell us how we can improve the browser and Developer tools.

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Help build the last independent browser. Write code, fix bugs, make add-ons, and more.

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Firefox Developer Edition

The browser made for developers

Inactive CSS

Firefox DevTools

Master CSS Grid

Fonts Panel

Build and Perfect your sites with Firefox DevTools

Inspector

Console

Debugger

Network

Storage panel

Responsive Design Mode

Visual Editing

Performance

Memory

Style Editor

Get the most out of Firefox Developer Edition

Speak up

Get involved

Download the Firefox browser made for developers

Build and Perfect your sites
with Firefox DevTools