Radicale

Radicale is a small calendar and contacts server that uses the CalDAV and CardDAV standards. It lets you sync events and address books with many standard apps.

Radicale stores calendars, to-do lists and contact cards on your own machine. Devices and desktop apps connect over standard protocols, so you can keep using the calendar and contact apps you already have. Data is stored as plain files in a simple folder structure, which makes backups easy to understand. It supports authentication options, access rules and TLS for secure connections. Plugins can extend its behaviour, and the documentation covers both a short local test setup and longer configurations for everyday use.

• Sync calendars and to-do lists over CalDAV
• Share contact lists over CardDAV
• Data stored as plain files in folders
• Authentication and access rules
• Optional TLS and plugins

Home users and small teams who want to keep calendars and contacts on their own server. It suits people who can set up a small Python service and, if needed, a reverse proxy.

Radicale is free software under the GPLv3 licence and has no paid tier. Costs come from the machine that runs it. Setup needs Python 3.9 or later, and you should take care with authentication and TLS once remote devices connect. The documentation includes a tutorial for running it as a service and a list of supported clients.