This is what I've been using, but it appears to be abandoned now?

I finally got the caldav part of it to work for a group of people using various flavors of Mac, Linux, and Windows -- PCs and phones. It was a huge pain in the ass, because each client accepted a different form of base-url-plus-calendar-locator, and some very non-technical users were on the other side of the planet, and it took weeks of trial and error before we got everything working.

Carddav looks hopeless, I can't even something that works between DavX5 on my android phone, and whatever the hell my wife's iPhone needs, and we're in the same room.