Overall, really positive interview experience. Had an initial call with the hiring manager, did a great job explaining the "why" of the project and team. Technical phone interview on HackerRank, pretty typical coding exercise, medium to hard difficulty. On-site interview had two more coding exercises, one was really challenging and the other was very simple, as well as a system design interview, and then lastly a leadership/behavioral interview. Throughout the interviews, everyone was very friendly and engaged, not combative like some other places I've interviewed. I also had lunch with a few folks not on the interview panel, food and conversation were both great. Throughout the entire process, from the first call to the offer negotiation, my recruiters were exceptional. I felt valued, informed, and welcomed. Suggestion: highly recommend reviewing Twitter's existing architecture in prep for the system design, lot of good videos and articles on the web that would through parts of it. Only negative is that each team's interview process seems different, so YMMV, and my experience doesn't reflect the same as other people I know that have interviewed at Twitter.