6 self-hosted options
Open-source alternatives to Microsoft 365
The best open-source alternative to Microsoft 365 is Nextcloud (AGPL-3.0, 37,298 GitHub stars). Mailcow stands out for the most recent release (2026-10, October 2026), and CryptPad stands out for a published Docker image.
About Microsoft 365: Microsoft's subscription suite of Office apps, Exchange mail and Teams chat.
Updated · data from GitHub, refreshed daily
Top picks
- Rank 1:
Nextcloud
nextcloud/server
Access and share your files, calendars, contacts, mail and more from any device, on your terms.
Active · last commit Oct 26, 2026
FeaturedFile Sync & StoragePHPStands out for the most GitHub stars.
- Rank 2:
Mailcow
mailcow/mailcow-dockerized
Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.
Active · last commit Oct 25, 2026
Email ServersJavaScriptDockerStands out for the most recent release (2026-10, October 2026).
- Rank 3:
CryptPad
cryptpad/cryptpad
Collaboration suite built to enable collaboration, synchronizing changes to documents in real time.
Active · last commit Oct 23, 2026
Office SuitesJavaScriptDockerStands out for a published Docker image.
At a glance
Microsoft 365 alternatives compared
Open-source apps come first, then source-available ones and apps whose license appsgit could not verify; within each group, projects with at least 12 commits in the last 12 months come before less active or archived ones, then by GitHub stars.
| App | Stands out for | License | GitHub stars | Commits (12 mo) | Last commit | Docker image |
|---|---|---|---|---|---|---|
| Nextcloud | the most GitHub stars | AGPL-3.0 | 37,298 | 8,041 | Oct 26, 2026 | No |
| Mailcow | the most recent release (2026-10, October 2026) | GPL-3.0 | 13,696 | 354 | Oct 25, 2026 | Yes |
| CryptPad | a published Docker image | AGPL-3.0 | 8,028 | 1,005 | Oct 23, 2026 | Yes |
| ONLYOFFICE | its Shell codebase | AGPL-3.0 | 7,054 | 28 | Oct 22, 2026 | Yes |
| SOGo | its Objective-C codebase | GPL-2.0 | 2,176 | 111 | Oct 22, 2026 | No |
| egroupware | – | GPL-2.0 | 299 | 3,547 | Oct 24, 2026 | No |
Full list
All 6 Microsoft 365 alternatives
Open any app for live stats, license details and a deploy option.
- 1
NextcloudFeatured
Access and share your files, calendars, contacts, mail and more from any device, on your terms.
File Sync & StorageStands out for the most GitHub stars. Nextcloud has 37,298 GitHub stars, uses the AGPL-3.0 license and had 8,041 commits in the last year.
- 2
Mailcow
Mail server suite based on Dovecot, Postfix and other open source software, that provides a modern Web UI for administration.
Email ServersDockerStands out for the most recent release (2026-10, October 2026). Mailcow has 13,696 GitHub stars, uses the GPL-3.0 license, ships a Docker image and had 354 commits in the last year.
- 3
CryptPad
Collaboration suite built to enable collaboration, synchronizing changes to documents in real time.
Office SuitesDockerStands out for a published Docker image. CryptPad has 8,028 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 1,005 commits in the last year.
- 4
ONLYOFFICE
Office suite that enables you to manage documents, projects, team and customer relations in one place.
Office SuitesDockerStands out for its Shell codebase. ONLYOFFICE has 7,054 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 28 commits in the last year.
- 5
SOGo
SOGo offers multiple ways to access the calendaring and messaging data. CalDAV, CardDAV, GroupDAV, as well as ActiveSync, including native Outlook compatibility and Web interface.
Groupware & CalendarsStands out for its Objective-C codebase. SOGo has 2,176 GitHub stars, uses the GPL-2.0 license and had 111 commits in the last year.
- 6
egroupware
Software suite including calendars, address books, notepad, project management tools, client relationship management tools (CRM), knowledge management tools, a wiki and a CMS.
Groupware & Calendarsegroupware has 299 GitHub stars, uses the GPL-2.0 license and had 3,547 commits in the last year.
Is there a free alternative to Microsoft 365?
Yes. All 6 apps on this page are open source and free to self-host, so you can replace Microsoft 365 without per-user fees. You pay only for the server.
Can I self-host an alternative to Microsoft 365 with Docker?
Yes. 3 of the 6 apps here publish a Docker image, including Mailcow, CryptPad and ONLYOFFICE, so you can run them on a home server or VPS with Docker Compose.
Which Microsoft 365 alternative is the most actively developed?
Nextcloud (AGPL-3.0), with 8,041 commits in the last 12 months. Activity is a good sign that bugs and security issues get fixed.
How is this list ranked?
Open-source apps come first, then source-available ones and apps whose license appsgit could not verify; within each group, projects with at least 12 commits in the last 12 months come before less active or archived ones, then by GitHub stars.