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Balsa vs Claws Mail: catalog facts
Balsa	Claws Mail
Free Free and open source under the GPL.	Free Free and open source under the GPL 3.0 or later.
Linux	Windows, macOS, Linux
Lightweight native GTK interface Fits in with the GNOME desktop	Opens and searches enormous mail folders without stalling Plugins for PGP, spam filtering, RSS and calendars ship with it
Linux only Smaller feature set than full PIM suites	Composes plain text by default; HTML mail sending is deliberately limited The interface is functional and looks like it was designed in 2004
Downloadable app	Downloadable app
Open source	Open source
License: GPL-2.0-or-later	License: GPL-3.0-or-later
No account needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 24, 2026	Official website Full listing and sources Checked September 21, 2026

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