Calendar

Bedework CalDAV - Java

Cosmo - Java

carldav - Java

sabre-io/dav - PHP

Radicale - Python

xandikos - Python

https://milton.io/

https://github.com/thomas-trendsoft/davserver

https://github.com/swordlordcodingcrew/fennel

Docker-Radicale - Docker

https://github.com/kristapsdz/kcaldav - C

CalDAV4j

https://github.com/tchapi/davis

https://github.com/miltonio/milton2

https://www.webdavsystem.com/server/creating_caldav_carddav/creating_caldav_server/