Radicale
Calendar & Contacts
Simple calendar and contact server with extremely low administrative overhead.
Actively maintained
Real momentum
GPL-3.0
Lightweight CalDAV and CardDAV server based on sabre/dav.
Baïkal is an open-source calendar & contacts project, with 3.3k GitHub stars and a health score of 70/100. It committed 29 times in the last twelve months across 8 of those months, and its status is actively maintained. Licence: GPL-3.0. It has real momentum, so treat it as a live competitor rather than a stale repository.
| Status | Actively maintained — Committed within the last 45 days. |
|---|---|
| Last commit | 2026-08-13 |
| Days since last commit | 4 |
| Commits, last 3 months | 13 |
| Commits, last 12 months | 29 |
| Months with activity | 8 of 12 |
| Last release | 2026-08-05 |
| Archived | No |
| Licence | GPL-3.0 |
| Category | Calendar & Contacts |
Health score combines commit recency, twelve-month commit volume, months with activity, release recency and archive state. Metadata refreshed August 2026.
Copyleft (GPL, AGPL, MPL): derivative work must stay open. AGPL also covers software offered over a network, which blocks most closed SaaS wrappers.
This matters most when you plan to sell a hosted version. A permissive licence means anyone — including a competitor with more capital — can do the same, so your defensibility has to come from distribution, support or data, not from the code.
Baïkal is shipping code consistently, so a buyer comparing your product will find a maintained free option. Price and position against the total cost of self-hosting it, not against the paid incumbent's list price.
Winnable, but differentiation is not optional. Pick one underserved segment and be visibly better for it rather than competing feature-for-feature with a free tool.
Actively maintained. Baïkal recorded 29 commits over the last twelve months, with activity in 8 of those months and 13 commits in the last quarter. Last commit: 2026-08-13. Last release: 2026-08-05. Committed within the last 45 days.
Baïkal is published under GPL-3.0. Copyleft (GPL, AGPL, MPL): derivative work must stay open. AGPL also covers software offered over a network, which blocks most closed SaaS wrappers.
8 open-source implementations, 7 of them actively maintained, led by Radicale at 4.9k stars. Saturation score 40/100 — Contested. Several maintained alternatives exist, but no one owns the category.
Calendar & Contacts
Simple calendar and contact server with extremely low administrative overhead.
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Calendar & Contacts
Open source CardDAV and CalDAV server with minimal administrative overhead, backed by a Git repository.
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