All-in-one Mail & Collaboration server. Secure, scalable and fluent in every protocol (IMAP, JMAP, SMTP, CalDAV, CardDAV, WebDAV).
Mail, calendars and contacts only.
alternatives to
Microsoft 365
Microsoft's office apps, mail and cloud storage, sold as a subscription. A closed product from Microsoft.
Side by side
| Tool | Fit | Stars | Licence | Terms | Self-hosted | Language | Latest | Last push |
|---|---|---|---|---|---|---|---|---|
| Stalwart | Partial | 15k | None detected | Open core | Yes | Rust | v0.16.25 | 2026-10-05 |
| mailcow | Partial | 14k | GPL-3.0 | Open source | Yes | JavaScript | 2026-09a | 2026-10-06 |
| ONLYOFFICE Docs | Partial | 7k | AGPL-3.0 | Open source | No | Shell | v9.4.0 | 2026-07-22 |
| ONLYOFFICE Desktop Editors | Partial | 5.5k | AGPL-3.0 | Open source | No | Unknown | v9.4.0 | 2026-05-21 |
| LibreOffice | Partial | 4.5k | GPL-3.0 | Open source | No | C++ | libreoffice-26.8.1.1 | 2026-10-06 |
| Collabora Online | Partial | 3.4k | Other | Open source | No | Shell | 25.04.7-mobile | 2026-10-06 |
| SOGo | Partial | 2.2k | GPL-2.0 | Open source | Yes | Objective-C | SOGo-5.12.11 | 2026-10-02 |
Every alternative
7 alternatives
mailcow: dockerized - 🐮 + 🐋 = 💕
Mail, calendars and contacts; ActiveSync for mobile clients.
- Language
- JavaScript
- Licence
- GPL-3.0
- Stars
- 14k
- Latest
- 2026-09a
- Last push
- 2026-10-06
ONLYOFFICE Docs is a free collaborative online office suite comprising viewers and editors for texts, spreadsheets and presentations, forms and PDF, fully compatible with Office Open XML formats: .docx, .xlsx, .pptx and enabling collaborative editing in real time.
Browser-based co-editing of Word, Excel and PowerPoint files, without mail and Teams.
Open-source office suite pack that comprises all the tools you need to work with documents, spreadsheets, presentations, PDFs, and PDF forms on Windows, Linux, and macOS
Desktop editors for Word, Excel and PowerPoint files, without mail or cloud storage.
Read-only LibreOffice core repo - no pull request (use gerrit instead https://gerrit.libreoffice.org/) - don't download zip, use https://dev-www.libreoffice.org/bundles/ instead
Desktop word processor, spreadsheet and presentations that open Office formats, without cloud services.
- Language
- C++
- Licence
- GPL-3.0
- Stars
- 4.5k
- Latest
- libreoffice-26.8.1.1
- Last push
- 2026-10-06
Issue tracker only. Active development is on Gerrit at https://gerrit.collaboraoffice.com/.
Browser editing of Word, Excel and PowerPoint files, without mail and Teams.
- Language
- Shell
- Licence
- Other
- Stars
- 3.4k
- Latest
- 25.04.7-mobile
- Last push
- 2026-10-06
SOGo is a very fast and scalable modern collaboration suite (groupware). It offers calendaring, address book management, and a full-featured Webmail client along with resource sharing and permission handling. It also makes use of documented standards (IMAP, CalDAV, CardDAV, etc.) and thereby provides native connectivity (without plugins) to many clients such as Microsoft Outlook, Apple iCal, the iPhone, Mozilla Lightning, and a plethora of mobile devices.
Webmail, calendars and contacts over IMAP, CalDAV and CardDAV, with ActiveSync for phones.
- Language
- Objective-C
- Licence
- GPL-2.0
- Stars
- 2.2k
- Latest
- SOGo-5.12.11
- Last push
- 2026-10-02
Head to head
- Collabora Online vs LibreOffice
- Collabora Online vs mailcow
- Collabora Online vs ONLYOFFICE Docs
- Collabora Online vs ONLYOFFICE Desktop Editors
- Collabora Online vs SOGo
- Collabora Online vs Stalwart
- LibreOffice vs mailcow
- LibreOffice vs ONLYOFFICE Docs
- LibreOffice vs ONLYOFFICE Desktop Editors
- LibreOffice vs SOGo
- LibreOffice vs Stalwart
- mailcow vs ONLYOFFICE Docs
- mailcow vs ONLYOFFICE Desktop Editors
- mailcow vs SOGo
- mailcow vs Stalwart
- ONLYOFFICE Desktop Editors vs SOGo
- ONLYOFFICE Desktop Editors vs Stalwart
- ONLYOFFICE Docs vs ONLYOFFICE Desktop Editors
- ONLYOFFICE Docs vs SOGo
- ONLYOFFICE Docs vs Stalwart
- SOGo vs Stalwart
About Microsoft 365
- Vendor
- Microsoft