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Citadel vs EGroupware: catalog facts
Citadel	EGroupware
Free Free and open source under the GNU GPL, with no paid edition.	Freemium Free Community Edition; the EPL edition and cloud hosting are paid.
Web, Self-hosted	Web, Self-hosted
Mail, calendar, contacts, forums, wiki and chat in one server Consistent rooms-based structure across features	Wide feature set from email and calendar to CRM and helpdesk Can be self-hosted or used as a German-hosted cloud service
The rooms metaphor differs from conventional mail servers Requires running and maintaining your own server	Some features are reserved for the paid EPL edition A large suite to set up and maintain on your own server
Self-hosted	Web application, Self-hosted, Hosted service
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.