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Zen BrowserSigmaOS
Free

Free and open source, funded by donations.

 Freemium

A free tier is available. Heavier use moves to a paid subscription.

Windows, macOS, Linux macOS
  • Vertical tabs, workspaces and split view built in, no extensions needed
  • Firefox engine, so Firefox extensions and containers work
  • Tabs live in named workspaces with separate logins, and each one can be marked done or locked, which…
  • Young project; interface changes between releases and bugs surface
  • A small team maintaining a Firefox fork is a real long-term risk
  • It is closed source, macOS-only, and the free tier is limited enough that regular use pushes you to…
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
Needs internet Not stated if it works offline

Checked September 21, 2026

Checked September 22, 2026

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