All alternatives
Best Open Source Alternatives to Outlook Calendar
Compare the best free and open-source alternatives to Outlook Calendar — self-hosted and desktop replacements you fully control, ranked by GitHub stars, license and platform support.
Curated by open-source.store · Updated August 2026 · 7 alternatives
Outlook Calendar
Proprietary SaaSOutlook Calendar alternatives compared
| Tool | License | Platforms | Self-hosted | |||
|---|---|---|---|---|---|---|
 Cal.com | 47,171 | AGPL-3.0 | WebDockerLinuxmacOS | Yes | Jul 2026 | Visit |
 Radicale | 4,864 | GPL-3.0 | LinuxmacOSWindowsDocker | Yes | Aug 2026 | Visit |
 Baïkal | 3,253 | GPL-3.0 | LinuxDockerWeb | Yes | Jul 2026 | Visit |
 SOGo | 2,140 | GPL-2.0 | LinuxDocker | Yes | Jul 2026 | Visit |
 DAViCal | 0 | GPL-2.0 | Linux | Yes | — | Visit |
 InfCloud | 0 | AGPL-3.0 | Web | Yes | — | Visit |
 Events | 0 | GPL-3.0 | Linux | No | — | Visit |
