CalDAV is a protocol for synchronizing calendars over the Internet. Built on WebDAV, which extends HTTP, CalDAV lets clients create, read, update, and delete calendar data, such as events and tasks, stored on a server. The data format is iCalendar (.ics).

CardDAV is similar, but for contacts and address books. It is also WebDAV-based and uses vCard (.vcf) as the data format.

Depending on the client, these are the URLs that they need to connect:

A smart client only needs to use https://YourHost.YourDomain.com and query the .well-known URL to access /caldav/calendar/, /carddav/contacts/. Some clients need the base URL, while others need the absolute URL.

Well-Known URL

https://YourHost.YourDomain.com/
https://YourHost.YourDomain.com/.well-known/

https://YourHost.YourDomain.com/.well-known/caldav
https://YourHost.YourDomain.com/.well-known/cardav

Base URL

https://YourHost.YourDomain.com/caldav/
https://YourHost.YourDomain.com/carddav/

Absolute URL

https://YourHost.YourDomain.com/caldav/calendar/
https://YourHost.YourDomain.com/caldav/tasks/
https://YourHost.YourDomain.com/caldav/notes/
https://YourHost.YourDomain.com/carddav/contacts/