Store your contacts and calendars on your own Synology NAS, away from the inquisitive eyes of Google, NSA and others.

Baïkal itself is an already existing, lightweight CardDAV (contacts) and CalDAV (calendar) server.
The source code is public, and available to everyone on GitHub. Baïkal is copyright (c) 2013 by Jérôme Schneider, the homepage is http://baikal-server.com.