I applied online and received a reply in about a week. It was an OA invitation on HackerRank. Basically, you need to finish it within five days. You can pick any date and time you like, but you need to let them know ahead of time. The assessment must be finished within 75 minutes.
The name of the quiz problem is also given ahead of time, called "Catching an Insider Trader." My suggestion is to read the questions carefully, because there are usually slight, subtle changes in the problem statement compared to those you find online.
It's a mid-size quiz called "Catching an Insider Trader."
The following metrics were computed from 1 interview experience for the Palantir Software Engineer role in Houston, Texas.
Palantir's interview process for their Software Engineer roles in Houston, Texas is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for Palantir's Software Engineer interview process in Houston, Texas.