I was poached by a recruiter who felt my skills aligned to SRE. I had a total of four interviews - an initial behavioural interview, a theoretical technical, a phone screen coding and finally an on-site. The whole process took about 2 months. In my experience, Google tried to make the entire thing extremely smooth and 'fair'. They make you feel super special and give you a lot of information, study material and time to do your best. They basically tell you what to study. The first 'technical' was sort of a gauge of my skills. I was asked a bunch of basic comp sci questions as well as other SRE fields that may be important e.g. O/S and Networking questions. I didn't have to do great in all of them but I'm guessing doing generally well in at least one area is important - I got all the programming/comp sci questions correct as well as a good amount of the O/S questions. The coding phone screen was actually not so hard. I think they focus on what you claim you were good at - in my case it was Java. The on-site was the 'hardest', however, I'd say overall it was fair. The questions were pretty much CTCI style and I didn't get anything too difficult. But I messed up the first round because the guy who interviewed me was a classic elitist and whenever I asked him questions he made me feel extremely stupid. He was getting noticeably frustrated and at the end walked out with a passive aggressive: "Well, good luck with the rest". The rest were *okay* except for the system design question. I was smashed with a sort of math-driven question with a bunch of numbers and components which really threw me off. I did terrible for this part and I knew it was over for me at this point. I got a rejection email about a week later and was lucky enough to receive feedback. I can see where I went wrong. My advice to candidates is study extremely hard, focus on the important areas they hint to you, and finally - don't feel bad if you don't get it. I was told by the guys who gave me system design interview that probably close to 50% of the employees at Google applied twice before they made it.

HR round after applying, then coding screening round, if passes, then final round which consists of four coding round or three coding and one design round. Problem difficulty medium to hard.