Pretty extensive interview. Took about a full 9-5. Very friendly team and managers I interacted with. You can express yourself easily in the technical interview, and no one is there to catch you not knowing something. The team is pretty helpful in hinting you in certain scenarios. Roughly a week after the interview, I got a call that they want to proceed with the process of making an offer. Comp and all negotiated Ok. They made it sound like, it's a done deal for 3 weeks, and awaiting CTO to comeback from vacation and sign the offer package. I was invited back after two weeks for lunch with the team and one of the managers as a show of good gestures, that they are serious about extending the offer, but still waiting on the CTO to come back. The end of the 4th week of the process, I received a call that the CTO has not signed off of the offer and thank you for your time. Reason stated as depth of technical skills. I do understand that that is a possibility of a rejection; however, a technical phone screen, 3x technical interviews (with senior engineers), 3x managerial/technical/process interviews with 2x manager, and head of the Department. and repeating for 3-4 weeks that this is happening and showing dislike towards me accepting other opportunities. Very unprofessional HR/recruiting staff and overall experience I had from this 4 weeks.