There are now three CalDAV implementations for Android:
These apps take different approaches:
- The Hypermatix app tries to synchronise the internal Android calendar store with a CalDAV server.
- aCal is a standalone calendar application which only supports calendars hosted on a remote CalDAV server.
- the caldav4j-apk is a free replacement for the google calendar which syncs with remote CalDAV servers.
The hypermatix app is "free as in beer" in the app store, while aCal is "free as in software" with the source code available on gitorious under the GPL v3 license. The app store version of aCal is sold for a token NZD$2 (or equivalent) to discourage accidental installation by people who don't actually want a CalDAV client, and to help keep the author in beer and pizza.