R

Radicale

Self-host

Small Python CalDAV and CardDAV server that stores calendars and contacts as plain files on disk.

Category
Calendar · Self-host
Cost
Self-host
Country
France
Licensing
FOSS
Platforms
Linux · macOS · Windows

Pros and cons

+ what works
  • +GPL-3.0, written in Python, runs on a Raspberry Pi or any small VM
  • +Standard CalDAV and CardDAV, so any third-party client (Thunderbird, DAVx5, Apple Calendar) works
  • +File-based storage means backups are just copying a directory
  • +Active project with regular releases (3.7.2 shipped April 2026)
watch out for
  • Defaults are conservative: lightweight by design, capped around 8 parallel connections out of the box
  • No built-in web UI for end users; calendar and contact management happens in the client
  • Operator owns everything: TLS, auth backend, backups, reverse proxy, and updates
  • Documented compatibility-first stance: project will deviate from strict RFC behavior to keep popular clients working

Privacy notes

Radicale runs on hardware you control and stores collections as iCalendar and vCard files under a configurable directory; no data leaves the box unless a client requests it. Since 3.5.0 the default config rejects all auth until the operator explicitly configures a backend (htpasswd, LDAP, OAuth2, PAM, or Dovecot), which closes the historical foot-gun of open instances. Data stays under the operator's jurisdiction since the user is the operator. Project stewardship sits with the Kozea community in France.

Tags

#foss · #python · #caldav · #carddav · #gpl-3.0

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