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Firefox vs Opera GX: catalog facts
Firefox	Opera GX
Free Free software from a non-profit-owned foundation. Mozilla sells separate subscription…	Free Free to download and use. The software is closed source.
Windows, macOS, Linux, Android, iOS	Windows, macOS, Linux, Android, iOS
Total Cookie Protection stops cookies following you between sites An engine that is not Chromium, which matters for the health of the web	The resource limiters cap how much CPU, memory and bandwidth the browser may take, which keeps it from…
A small number of sites are still built and tested only against Chromium Mozilla’s revenue comes largely from a search deal, which shapes some defaults	It is closed source, the styling is loud and hard to tone down, and it carries Opera's same…
Downloadable app	Downloadable app
Open source	Closed source
License: MPL-2.0	License not stated
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 20, 2026	Official website Full listing and sources Checked September 22, 2026

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