Self Hosted Calendaring and Contacts Management calypso

The Etebase server (so you can run your own)

Android app to sync contacts, calendars and tasks without a server using DecSync

🗓 A simple, fully translatable admin interface for sabre/dav based on Symfony 5 and Bootstrap 4, largely inspired by Baïkal.

Open-source CalDAV/CardDAV suite and sync app for Android.