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Zimbra vs Nextcloud Calendar: catalog facts
Zimbra	Nextcloud Calendar
Paid Sold in several editions under Zimbra's license terms; see the edition comparison.	Free Free app for Nextcloud servers.
Web, Self-hosted	Web, Self-hosted
Mail, calendar and contacts in one web client Can be run on your own servers	Calendars stay on your own server CalDAV sync with standard clients
Aimed at organisations rather than individuals Running a mail server takes administration effort	Requires a running Nextcloud server Not a standalone app
Self-hosted, Hosted service	Self-hosted
Closed source	Open source
License not stated	License not stated
Not stated if an account is needed	Account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked October 2, 2026

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