Radicale
Radicale provides an effective solution for sharing calendars, to-do lists, and contact lists using CalDAV and CardDAV protocols. It facilitates management of events, todos, journal entries, and business cards without heavy configurations. The server supports access control through authentication and ensures secure connections with TLS. With data arranged in an accessible folder structure, management is straightforward. Radicale is free software under GPLv3 license, compatible with numerous CalDAV and CardDAV clients, and supports plugin-based extensions. Refer to the documentation for detailed guidance and explore discussions for enhanced server operations.