SOGo
GroupwareScalable groupware server with webmail, calendar and contacts
Replaces Microsoft Exchange, Microsoft 365
Best Cross-Platform Groupware for self-hosting
The 7 best Cross-Platform groupware you can self-host, ranked by community traction.
Nextcloud Groupware
GroupwareMail, calendar and contacts bundle for Nextcloud
Replaces Microsoft 365, Google Workspace
Openmeetings
GroupwareVideo conferencing, instant messaging, whiteboard, collaborative
Kontact
GroupwareIntegrated personal information manager for KDE
Replaces Microsoft Outlook
Digiwall
GroupwareCreate multimedia collaborative walls for in-person or remote work
Cozy Cloud
GroupwarePersonal cloud where you can manage and sync your files, notes,
Zimbra Collaboration
GroupwareEmail, calendar, collaboration server with Web interface and lots of
No apps match these filters.
Every option here is open-source and self-hostable, tagged Cross-Platform within the groupware category. Compare them on the individual app pages for setup difficulty and resource requirements.