Proton Calendar

Proton Calendar is the calendar app from Proton AG, the Swiss company behind Proton Mail, Proton Drive and Proton VPN. It works like a regular planner, with day, week and month views, recurring events, multiple reminders, time-zone support and a home-screen widget.

The difference is privacy: event titles, descriptions, locations and guest lists are stored with zero-access encryption, and events exchanged between Proton users are end-to-end encrypted, so Proton cannot read your schedule. There are no ads or trackers. Invitations work with people on other calendar services too, and your calendar stays in sync with the web version.

The app is free to use with a Proton account; paid Proton plans raise limits such as the number of calendars you can keep. The source code is published and the encryption has been independently audited.

Source: Proton AG, https://proton.me/calendar/download . Developer: Proton AG. Licence: GPL-3.0 (app source code). The download on this page is the official APK served from proton.me (version 2.34.1, released 29 September 2026); that link always serves Proton's latest direct build.