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SOGo vs Zoho Calendar: catalog facts
SOGo	Zoho Calendar
Free Free and open source; paid premium support is offered separately.	Freemium Free to start, with paid Zoho plans for business features.
Web, Self-hosted	Web
Webmail, calendars and contacts in one self-hosted server CalDAV, CardDAV and ActiveSync support for native and mobile clients	Team calendars with availability checks Built-in appointment and resource booking
Needs existing mail and directory servers to integrate with Outlook support depends on a separate CalDAV synchronizer	Hosted service, with data stored by Zoho Most useful inside the wider Zoho ecosystem
Self-hosted	Web application
Open source	Closed source
License: GPL-2.0-or-later / LGPL-2.0-or-later	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 September 23, 2026	Official website Full listing and sources Checked October 2, 2026

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