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Mercury vs GNU IceCat: catalog facts
Mercury	GNU IceCat
Free Free and open source.	Free Free software from the GNU Project with no paid tier.
Windows, macOS, Linux	Linux
Compiler-optimized Firefox builds Privacy patches drawn from LibreWolf, Waterfox and IceCat	Contains only free software, with no nonfree add-on recommendations LibreJS blocks nonfree JavaScript
Maintained by a single developer Updates can trail official Firefox releases	Blocking JavaScript breaks many modern sites until you allow scripts Builds are distributed from a third-party download page
Downloadable app	Downloadable app
Open source	Open source
License: MPL-2.0	License not stated
No account needed	No account needed
Not stated if it 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 23, 2026

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