Lightweight CalDAV and CardDAV server. It is designed for simple self-hosting with low resource usage and strict adherence to open standards.

End-to-end encrypted sync for contacts and calendars. It provides zero-knowledge sync and works seamlessly with your existing apps to keep data private.

Community-maintained offline calendar app. It abuses no permissions, offers a clean UI, and is completely free of ads and trackers.

Cloud sync service for CalDAV and CardDAV. It relies on open standards to provide privacy-focused, reliable cross-device synchronization.

Encrypted calendar from Proton. It utilizes zero-access encryption and Swiss privacy laws to keep your schedule and events completely secure.

Encrypted calendar integrated with Tuta Mail. It features end-to-end encryption, anonymous signup, and is powered by green energy.