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Firefox ESRBasilisk
Free

Free and open source; Mozilla offers optional paid professional support for organisations.

 Free

The open-source application is available without a license fee.

Windows, macOS, Linux Windows, macOS, Linux
  • Long-term stable feature set for managed deployments
  • MSI and PKG installers plus group policy templates
  • Runs classic XUL extensions that no current browser supports
  • Independent of Chromium and of current Firefox
  • New features arrive later than in regular Firefox
  • Mainly aimed at organisations rather than home users
  • Small development team, so security fixes and web compatibility lag
  • Many modern sites do not work correctly
Downloadable app Downloadable app
Open source Open source
License: MPL-2.0 License: MPL-2.0
No account needed Not stated if an account is needed
Not stated if it works offline Not stated if it works offline

Checked September 24, 2026

Checked September 22, 2026

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