DAViCal

DAViCal implements the CalDAV protocol to provide a server‑based calendar store that keeps events in iCalendar format within a PostgreSQL database. It allows multiple clients—such as Mozilla Lightning, Evolution, Apple iCal/iOS and other CalDAV‑compatible applications—to read and write shared calendars, supporting basic delegation of access and free/busy scheduling. The server also offers read‑only WebDAV access for compatibility with older tools, though write‑through WebDAV is not recommended.

The software is self‑hostable and runs on typical web stacks that include PHP 5 and a PostgreSQL backend; it has been deployed on Linux, FreeBSD, macOS and, with caveats, Windows. Installation and configuration guidance is provided through a wiki and documentation, while community support is available via an IRC channel and a mailing list.

Released under GPL‑2.0, DAViCal is free, open‑source, and maintained as a stable project without subscription or tiered licensing requirements, making it suitable for individuals or organizations that need a controllable, standards‑compliant calendar sharing solution.