Their website describes the process well.
I had a few phone interviews (with maybe one to two technical questions per call), and then was flown to their HQ in Palo Alto. You sign an NDA when you walk in, so I'm not sure how specific I can get, but as their site says, there is a series of technical interviews lasting approximately 45 minutes each.
My questions mostly related to data structures and algorithms. Some were easy, others were challenging, but they are doable if you don't give up and ask for hints when you need them.
Modify existing data structure X so that it can also do Y.
The following metrics were computed from 6 interview experiences for the Palantir Forward Deployed Software Engineer role in Palo Alto, California.
Palantir's interview process for their Forward Deployed Software Engineer roles in Palo Alto, California is fairly selective, failing a large portion of engineers who go through it.
Candidates reported having very good feelings for Palantir's Forward Deployed Software Engineer interview process in Palo Alto, California.