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SeaMonkey vs Basilisk: catalog facts
SeaMonkey	Basilisk
Free The software is free under its open-source licence. Hosting, hardware and external…	Free The open-source application is available without a license fee.
Windows, macOS, Linux	Windows, macOS, Linux
It is the continuation of the old Mozilla Application Suite, so browsing, mail, news and page editing live…	Runs classic XUL extensions that no current browser supports Independent of Chromium and of current Firefox
It tracks an older Firefox codebase, so web compatibility and security hardening trail the current browsers.	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
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 22, 2026

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