I had one phone interview + 4 on-site interviews: 2 coding, 1 cultural + coding, 1 system design. My experience suggests that I should have not waste my time with Facebook. It seems that they just interview with people without giving them offer. I had a perfect day at my on-site interview. I heard a few others were like me as well. None of us got an offer. In my case, two of the interviewers were really surprised with my answers and I finished 15 minutes before the time goes up and we chat the rest of the time. One of the interviewers told me that she believes Facebook should hire less people to have enough challenges for the current employees. Recruiters at Facebook are also terrible. They respond to your emails with template answers and unfortunately have very low technical knowledge.