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18 self-hosted Microsoft 365 alternatives

Microsoft 365 is Microsoft's commercial productivity suite combining Office apps, OneDrive cloud storage, and collaboration services. It is subscription-based. These open-source apps let you replace Microsoft 365 with software you host and control yourself.

Best self-hosted Microsoft 365 alternatives

Nextcloud

File Sync & Storage

Self-hosted content collaboration and file sync platform

Replaces Dropbox, Google Drive

★ 36.4k Medium setup AGPL-3.0

Docker Mailserver

Production-ready, config-driven mail server in a container

Replaces Google Workspace, Microsoft 365

★ 18.7k Medium setup MIT

Mail-in-a-Box

Turn a fresh server into a working mail server

Replaces Google Workspace, Microsoft 365

★ 15.4k Easy setup CC0-1.0

CryptPad

File Sync & Storage

End-to-end encrypted collaboration suite

Replaces Google Drive, Microsoft 365

★ 7.8k Medium setup AGPL-3.0

Mailu

Simple yet full-featured Docker mail server

Replaces Google Workspace, Microsoft 365

★ 7.4k Medium setup MIT

ONLYOFFICE Docs

Document Management

Online office suite for documents, sheets, and slides

Replaces Google Docs, Microsoft 365

★ 6.8k Medium setup AGPL-3.0

Maddy Mail Server

Composable, all-in-one mail server in Go

Replaces Google Workspace, Microsoft 365

★ 6.1k Medium setup GPL-3.0

Mox

Modern, secure all-in-one mail server

Replaces Google Workspace, Microsoft 365

★ 5.8k Easy setup MIT

Collabora Online

Document Management

Self-hosted online office suite based on LibreOffice

Replaces Google Docs, Microsoft 365

★ 3.3k Medium setup MPL-2.0

OnlyOffice Community Server

Collaboration server pairing with the ONLYOFFICE editors

Replaces Microsoft 365

★ 3.2k Medium setup Apache-2.0

SOGo

Scalable groupware server with webmail, calendar and contacts

Replaces Microsoft Exchange, Microsoft 365

★ 2.1k Hard setup GPL-2.0

Nextcloud Groupware

Mail, calendar and contacts bundle for Nextcloud

Replaces Microsoft 365, Google Workspace

★ 1.2k Medium setup AGPL-3.0

LibreOffice Online

Browser-based office suite from the LibreOffice project

Replaces Microsoft 365, Google Docs

★ 649 Hard setup MPL-2.0

Calligra Suite

Graphic art and office suite from KDE

Replaces Microsoft 365

★ 300 Medium setup GPL-2.0

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

Citadel

All-in-one groupware, mail and collaboration server

Replaces Microsoft Exchange, Microsoft 365

★ 100 Medium setup GPL-3.0

Tine

Professional open-source groupware and CRM

Replaces Microsoft 365, Google Workspace

★ 21 Medium setup AGPL-3.0

Compare Microsoft 365 alternatives

Switching from Microsoft 365

Moving off Microsoft 365 means trading a managed subscription for a service you run yourself. The payoff is ownership: no per-seat pricing, no vendor lock-in, and full control of your data. Start with the option above that matches your setup-difficulty comfort level — every app links to a detailed specs page and head-to-head comparisons.