We didn't design Keybase's chat API to match any messaging standard, but the number of calls into it are very few and flexible, and we're open to change.

As it is right now, I imagine it would be very easy to write a library that acts as a bridge to other interfaces, if that's of interest.

There are calls to see into your "inbox" which is the set of conversations, read messages, even peek at unread messages. And of course send messages, too.