Compare software

Proton CalendarTimeTree
Freemium

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

 Freemium

Free with ads; Premium costs 4.49 USD per month or 44.99 USD per year, varying by region.

Android, iOS, Web Android, iOS
  • End-to-end encryption of event details
  • Built-in scheduling for booking meetings
  • Multiple shared calendars for different groups
  • Simple invite-based sharing
  • Requires a Proton account
  • Works best within the Proton ecosystem
  • Free version shows ads
  • File attachments and some views require Premium
Downloadable app, Web application, Hosted service Downloadable app
Closed source Closed source
License not stated License not stated
Account needed Not stated if an account is needed
Not stated if it works offline Not stated if it works offline

Checked September 23, 2026

Checked October 1, 2026

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