The interview process was very straight-forward. I applied online and was contacted for a phone interview with the SDR manager. The conversation went well, unfortunately they decided to move forward with other candidates. The only complaint I have was the lack of feedback received. The rejection letter stated "if you have any questions, I am here to help". I would recommend not putting that line in the email if you have no intention of responding or providing feedback.

It's a 3 hour panel interview. 3 hours sounds like a long time but this is very beneficial because you meet every level of personnel on the team and get to understand their unbiased day to day basis. You get a very good idea during the interview whether or not HackerRank is a good fit for you the candidate which is nice.