Compare software

EteSyncProton Calendar
Freemium

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

 Freemium

Free account available, with paid Proton plans and a business version.

Android, iOS, Web, Self-hosted Android, iOS, Web
  • Zero-knowledge end-to-end encryption
  • Works with existing contact and calendar apps
  • End-to-end encryption of event details
  • Built-in scheduling for booking meetings
  • Hosted service requires a paid plan after the trial
  • Desktop apps need the separate DAV bridge
  • Requires a Proton account
  • Works best within the Proton ecosystem
Downloadable app, Web application, Self-hosted, Hosted service Downloadable app, Web application, Hosted service
Open source Closed source
License not stated License not stated
Account needed Account needed
Not stated if it works offline Not stated if it works offline

Checked October 1, 2026

Checked September 23, 2026

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