This is cool. The first project that attempted a sort of shared address book was Plaxo, co-founded by Sean Parker of Napster fame back in 2002. But it was proprietary and centralised, so while I liked the idea, I didn't trust it.

Are you imagining it sharing data over some kind of open protocol(s), so communities can host their own contact directory and connect with each other?

This is how a shared contact card could look like.
#privacy #opensource #selfhosted #addressbook