Radicale

Radicale is a lightweight CalDAV and CardDAV server for syncing calendars, to-do lists, and contacts with a wide range of client applications. It focuses on simple deployment and straightforward storage, keeping data on the filesystem in a readable folder structure.

Key Features

• CalDAV and CardDAV support for calendars, tasks, journals, and contacts
• HTTP-based access compatible with many desktop and mobile DAV clients
• Filesystem storage with a simple folder layout (no database required)
• Authentication to restrict access to collections
• TLS support for encrypted connections
• Plugin system to extend and customize behavior

Use Cases

• Self-hosted calendar and contact sync for personal or family use
• Shared team calendars and address books for small groups
• Lightweight DAV backend for apps and devices that support CalDAV/CardDAV

Limitations and Considerations

• Filesystem-based storage may be less suitable than a database for very large, high-concurrency deployments

Radicale is a solid choice when you want standards-based DAV syncing with minimal operational overhead. Its simple storage model and extensibility make it practical for small to medium deployments needing reliable calendar and contact synchronization.