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Proton Calendar

What it is

Proton Calendar is a privacy-focused, end-to-end encrypted calendar service developed by Proton (the makers of Proton Mail).

What problem it solves

It provides a secure and private way to manage schedules and events without exposing data to service providers or third-party advertisers.

Where it fits in the stack

Orchestration / Personal Information Management. It serves as a secure alternative to cloud calendars like Google Calendar or Outlook.

Typical use cases

  • Managing sensitive personal or business schedules.
  • Encrypted event invitations and sharing.
  • Cross-platform synchronization across web, Android, and iOS.

Strengths

  • Privacy: End-to-end encryption for event details (title, description, location, participants).
  • Security: Part of the Proton ecosystem with strong authentication and data protection.
  • Open Source: The client-side code is open source and audited.

Limitations

  • Integration: Limited API and third-party integration compared to Google Calendar (no direct CalDAV support without Proton Bridge).
  • Features: Fewer advanced features (e.g., complex scheduling rules) compared to mature competitors.

When to use it

  • When privacy and data security are the top priorities for calendar management.
  • If you are already using the Proton ecosystem (Mail, Drive, VPN).

When not to use it

  • If you require deep integration with many third-party automation tools that do not support Proton.
  • If you need native CalDAV access without using a bridge or local synchronization tool.

Sources / references

Contribution Metadata

  • Last reviewed: 2026-03-30
  • Confidence: high