Firefox Quantum: 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)

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Firefox Developer Edition — English (US)

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Faster Performance

A Next-Generation CSS Engine

Firefox has been rebuilt from the ground up to be faster and more powerful than ever. This includes a new CSS engine that has state-of-the-art innovations and is blazingly fast.

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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.

Design. Code. Test. Refine.

Build and Perfect your sites
with Firefox DevTools

Inspector

Inspect and refine code to build pixel-perfect layouts.
Console

Track CSS, JavaScript, security and network issues.
Debugger

Powerful JavaScript debugger with support for your framework.
Network

Monitor network requests that can slow or block your site.
Storage panel

Add, modify and remove cache, cookies, databases and session data.
Responsive Design Mode

Test sites on emulated devices in your browser.
Visual Editing

Fine-tune animations, alignment and padding.
Performance

Unblock bottlenecks, streamline processes, optimize assets.
Memory

Find memory leaks and make your application zippy.
Web Audio

The only developer tool for inspecting the Web Audio API.
Scratchpad

Edit, write, run and execute JavaScript in real time.
Style Editor

Edit and manage all your CSS stylesheets in your browser.