The interview process is selective, and drawn out. But for good reason. Palantir hires the best people, and is very selective about who it brings in. The interview process covered all possible scenarios that someone working at Palantir would encounter. Algorithms, business scenarios etc.

I had behavioral interviews and then 4 in person interviews. The behavioral was straightforward. There was also a data query interview where they taught you a new "language" and had you execute basic queries in it. Then there was a system design interview. I had two of these. The last one they asked me if I was deployed to the moon to identify new species of alien what kind of system would I build.