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Waterfox vs Zen Browser: catalog facts
Waterfox	Zen Browser
Free Free and open source under MPL-2.0. Development is funded by donations.	Free Free and open source, funded by donations.
Windows, macOS, Linux	Windows, macOS, Linux
Telemetry and data collection are removed from the build, not just disabled in preferences Ad blocking and private, anonymised DNS are on by default	Vertical tabs, workspaces and split view built in, no extensions needed Firefox engine, so Firefox extensions and containers work
One small team tracking Mozilla, so security updates land after Firefox's The project has changed hands in the past, which matters if you are picking it on trust	Young project; interface changes between releases and bugs surface A small team maintaining a Firefox fork is a real long-term risk
Downloadable app	Downloadable app
Open source	Open source
License: MPL-2.0	License: MPL-2.0
No account needed	No account needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 21, 2026	Official website Full listing and sources Checked September 21, 2026

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