The fact that Google advertises their servers as supporting CardDAV is an insult to anyone who does try to be standards compliant.

The Google CardDAV server has similarities to what we call CardDAV. For very simple, controlled stuff, it may be possible to pretend it is.

For anything advanced, avoid it at all cost.

Radicale is a complete calendar and contact storing and manipulating solution. It can store multiple calendars and multiple address books.

Calendar and contact manipulation is available from both local and distant accesses, possibly limited through authentication policies.

It aims to be a lightweight solution, easy to use, easy to install, easy to configure. As a consequence, it requires few software dependencies and is pre-configured to work out-of-the-box.

SOGo is fully supported and trusted groupware server with a focus on scalability and open standards. SOGo is released under the GNU GPL/LGPL v2 and above.

SOGo provides a rich AJAX-based Web interface and supports multiple native clients through the use of standard protocols such as CalDAV, CardDAV and GroupDAV.