I applied through an employee referral. I interviewed at Meta
Interview
Had a phone interview followed by on site. Phone interview was good and the interviewer was very friendly. During onsite, I had about 5 one one one interviews. My interviews started on a bad note - the recruiter was late to pick me up from the lobby and my first interviewer came 10 minutes late. He then rushed me into a system design question. I outlined the initial design and checked with him if there were any specific directions he wanted to go into but got no response. I then kept working on the design question without him giving me any feedback. When there were only 5 minutes left, he started asking some questions on how some scenarios would work. I always thought that interviews were supposed to be a discussion rather than the candidate talking and other people listening but perhaps its different at Facebook.
Other interviews were also average - my third interviewer was a girl who seemed too full of herself and kept being very sarcastic. My fourth interviewer hardly showed any interest in my thesis work though he was a very experienced guy so its possible, they are able to absorb everything without even listening.
I applied online. The process took 4 weeks. I interviewed at Meta (Madrid) in Jan 2015
Interview
One phone screen and one Skype interview. The whole process was very quick to set-up, and I received my offer just a couple of days after my last interview. This is the best interview experience that I've had with a company.
Interview questions [1]
Question 1
Given a the price of a stock over time in an array, write an algorithm that identifies the optimum time time to buy the stock and the optimum time to sell in order to get the largest profit. You can only traverse the array one time.
I applied online. The process took 2 weeks. I interviewed at Meta (New York, NY) in Dec 2015
Interview
Applied online, contacted by recruiter in ~2 weeks. Had a phone interview. The interviewer did not say much, and when I had asked if I was going in the right direction, he said things along the lines of, whatever you think is right, which was not helpful at all. The question itself was moderately difficult, and would be really hard to solve without a bit of help, in my opinion, and the interviewer didn't seem to care much. He was pretty quiet the entire time, which made me nervous, but I suppose that is my own fault too. Overall, the phone round was pretty tough, and I would say to know your way around arrays and sorting very well.