I find it ironic that throughout the process, many interviewers insisted that the company has a very technical high bar, yet they have been using the same interview questions for the past 4 years. You would think if they had such a high technical bar, they could come up with new/more than one set of questions. I did very well on all 3 technical interviews (as I already had the answers) yet somehow did not move to the final round. I suspect it was my system design interviewer who gave me a "no hire" because unlike the 2 coding rounds, where I ran my code through many test cases and passed all of them, you cannot do this with system design. There is no objective way/machine to verify your answer. Also, he seemed annoyed and upset throughout the interview, almost like he didn't want to be there. Despite presenting a valid system design, I left this interview a little skeptical because of the interviewer's bad mood as well as the fact that he did not ask ANY questions or probe into my design at all. A normal system design would have questions like "how would you handle if we reach x DAU?" or "what happens if we start having bursts of traffic? How would you change your design?" None of that, just an angry face watching me. Overall, I had positive experience because I have nothing to complain about aside from not understanding why I didn't move forward. But perhaps if you get a different interviewer for system design or you get him on a day when he is in a better mood, this won't happen. I gave it very easy because the answers are all here in this thread.