Compare software

Zimbra vs Horde Groupware: catalog facts
Zimbra	Horde Groupware
Paid Sold in several editions under Zimbra's license terms; see the edition comparison.	Free Free and open source with no paid tier.
Web, Self-hosted	Web, Self-hosted
Mail, calendar and contacts in one web client Can be run on your own servers	Full groupware suite beyond mail, including tasks, notes and time tracking CalDAV, CardDAV and ActiveSync sync
Aimed at organisations rather than individuals Running a mail server takes administration effort	Requires running and maintaining a PHP server Older codebase with a long history of security fixes to track
Self-hosted, Hosted service	Self-hosted
Closed source	Open source
License not stated	License: LGPL/GPL
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 1, 2026	Official website Full listing and sources Checked September 23, 2026

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