Kalenderchen is a simple and easy-to-use calendar app that focuses on privacy and data protection. Developed by Daniel Manger Software, this Android app offers optional synchronization of multiple devices with end-to-end encryption. The app also has its own calendar cloud infrastructure on a German server, which is independent of the major providers.

One of the unique features of Kalenderchen is that it stores appointments and events on the device in a separate, isolated database. This ensures that other apps cannot access the calendar data even if they request access to the device's calendar during installation. Moreover, you do not need to provide any personal information to use the synchronization feature.

Kalenderchen is completely ad-free, and it also offers synchronization with the Windows PC version of the app. The app supports multiple calendar accounts, and it comes pre-loaded with holidays for all German states, Austria, and Switzerland. Additionally, it includes an easy-to-use task list that can be organized into categories and lists.