Firefox Developer Tools

A set of tools for inspecting and editing web code.
Our team works closely with the community and is always happy to
welcome new contributors.

Get Involved

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

Speak Up

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

Features

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

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.

Helpers

VS Code Debugger for Firefox

Debug your JavaScript code running in Firefox from VS Code.