The world’s most secure calendar
Proton Calendar is the world’s only calendar that uses end-to-end encryption and cryptographic verification to protect your entire schedule.
Need a secure calendar for work? Discover Proton for Business.


Secured by strong encryption
End-to-end encryption
With Proton Calendar, all of an event’s critical information, like the title, description, location, and attendees, are stored securely and privately with end-to-end encryption. Not even Proton can read your event details.
Elliptic curve cryptography
Proton Calendar leverages advanced, high-performance elliptic curve cryptography (ECC Curve25519) to secure your data. This happens automatically in the background without requiring any action from you.
Open source and independently audited
Keep participants private

Cryptographic verification

The signature of the data cryptographically ensures that each type of data was created and edited by the specified author and guarantees that nobody (not even Proton) has tampered with your events.
This cryptographic verification happens automatically in the background without requiring any action from you.