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Best API Groupware for self-hosting

The 11 best API groupware you can self-host, ranked by community traction.

Calcom Calendar

Open-source scheduling and appointment booking platform

Replaces Calendly, Doodle

★ 47.3k Medium setup AGPL-3.0

Easy!Appointments

Open-source web appointment scheduler

Replaces Calendly, Acuity Scheduling

★ 4.3k Easy setup GPL-3.0

ZenTao

Open-source project and team collaboration platform

Replaces Jira, Confluence

★ 1.7k Medium setup AGPL-3.0

Cozy

Personal cloud platform with contacts and calendar

Replaces Google Workspace

★ 1.3k Hard setup AGPL-3.0

EGroupware

Web-based groupware and team collaboration suite

Replaces Microsoft 365, Google Workspace

★ 295 Medium setup GPL-2.0

Group-Office

Web-based groupware and CRM with email and calendar

Replaces Microsoft 365, Google Workspace

★ 275 Medium setup AGPL-3.0

Kolab Groupware

Open-source groupware server with mail and calendaring

Replaces Microsoft Exchange, Zimbra

★ 200 Hard setup AGPL-3.0

Feng Office

Web-based collaboration and project management suite

Replaces Basecamp, Microsoft Project

★ 106 Medium setup AGPL-3.0

Kopano Groupware Core

Open-source collaboration platform with Outlook support

Replaces Microsoft Exchange

★ 60 Hard setup AGPL-3.0

Tine

Professional open-source groupware and CRM

Replaces Microsoft 365, Google Workspace

★ 21 Medium setup AGPL-3.0

Cozy Contacts

Contacts management app for the Cozy personal server

Replaces Google Contacts

★ 11 Medium setup AGPL-3.0

Every option here is open-source and self-hostable, tagged API within the groupware category. Compare them on the individual app pages for setup difficulty and resource requirements.