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Cyrus IMAP vs DAViCal: catalog facts
Cyrus IMAP	DAViCal
Free Free and open source.	Free Free software under the GNU General Public License.
Linux, Self-hosted	Linux, Self-hosted
Mail, calendars and contacts in one server JMAP support alongside IMAP	Calendar delegation and shared access between users Free/busy scheduling for meetings
Complex to configure compared with all-in-one servers No bundled webmail	Requires PostgreSQL and a PHP web server Setup is more involved than lighter CalDAV servers
Self-hosted	Self-hosted
Open source	Open source
License not stated	License: GPL-2.0
No account 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 24, 2026	Official website Full listing and sources Checked October 2, 2026

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