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vdirsyncerEteSync
Free

Free and open source.

 Freemium

The hosted service is paid after a free trial; running your own server is free.

macOS, Linux, Command line Android, iOS, Web, Self-hosted
  • Two-way sync for CalDAV and CardDAV
  • Keeps calendars and contacts as local files
  • Zero-knowledge end-to-end encryption
  • Works with existing contact and calendar apps
  • Command line only, with no graphical interface
  • Needs a configuration file before first use
  • Hosted service requires a paid plan after the trial
  • Desktop apps need the separate DAV bridge
Downloadable app Downloadable app, Web application, Self-hosted, Hosted service
Open source Open source
License: BSD-3-Clause License not stated
No account needed Account needed
Works offline Not stated if it works offline

Checked October 2, 2026

Checked October 1, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.