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Firefox Developer Tools vs Web Developer: catalog facts
Firefox Developer Tools	Web Developer
Free Free and included with Firefox.	Free Free and open source under the GPL.
Windows, macOS, Linux	Browser extension
Built into Firefox with nothing extra to install Can debug Firefox for Android remotely	Dozens of page manipulations one click away, many still missing from devtools Same toolbar across Chrome, Firefox and Edge
Only available inside Firefox Tests Firefox's engine, so other browsers still need their own tools	Much of its original value is now covered by built-in developer tools Interface is a dense menu-driven toolbar
Downloadable app	Browser extension
Open source	Open source
License: MPL-2.0	License: GPL-3.0
No account needed	Not stated if an account is needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 22, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.