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TimeTreeProton Calendar
Freemium

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

 Freemium

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

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