- Shares calendars through CalDAV, WebDAV and HTTP.
- Shares contacts through CardDAV, WebDAV and HTTP.
- Supports events, todos, journal entries and business cards.
- Works out-of-the-box, no installation nor configuration required.
- Can warn users on concurrent editing.
- Can limit access by authentication.
- Can secure connections.
- Works with many CalDAV and CardDAV clients.
Here is a blog post that provides some instructions on how to set it up and synchronize contacts and calendars between multiple services and applications.