European CALENDAR Alternatives

Proton Calendar is a Swiss-based encrypted online calendar service that keeps event data private with end-to-end encryption and Swiss privacy protection.

Tuta Calendar is a German encrypted calendar service launched in 2014 that provides end-to-end encryption for scheduling and communications.

Online calendar service for individuals, families, schools, clubs, and organisations.

Cross-platform service for syncing and sharing contacts, calendars, and tasks across devices and teams.