Compare software

Citadel vs tine Groupware: catalog facts
Citadel	tine Groupware
Free Free and open source under the GNU GPL, with no paid edition.	Free Open-source software; the research does not detail any paid offerings.
Web, Self-hosted	Web, Self-hosted
Mail, calendar, contacts, forums, wiki and chat in one server Consistent rooms-based structure across features	Email, calendar, contacts and tasks in one platform Resource planning for shared appointments
The rooms metaphor differs from conventional mail servers Requires running and maintaining your own server	Website and documentation mostly in German Aimed at organisations rather than individual users
Self-hosted	Self-hosted
Open source	Open source
License: GPL	License not stated
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 October 2, 2026	Official website Full listing and sources Checked October 2, 2026

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