I applied online without a referral. Recruiter contacted me after 10 days and sent an online coding challenge on HackerRank. Online challenge was 2 questions in 120 minutes. First one took 5-10 minutes, it was trivial. Second question was a bit more complex. Straightforward solution was not hard to code but it was open to improvements using appropriate data structures. I was able to pass all test cases in the given time. A few days later, recruiter contacted me again to schedule a technical phone screen with one of the forward deployed software engineers. I had the interview next week on Skype using HackerRank CodePair. The interviewer explained the projects they are working on briefly. We have talked a bit about my background then moved onto coding. It was 2 different questions lasted 45 minutes in total. First one was a simple string manipulation question. Second question was DFS on a grid. He asked a few follow-ups related to data structures, alternative solutions and running time complexity; I answered them verbally. I coded in C++. They are fine with any OO language you choose. I was also able to ask questions at the end. He was so friendly and frank, by far the best interviewer I met. It was fun. On the same day, they have invited me to London for on-site interviews. Recruiters were great arranging everything. They covered flights, accommodation, visa fees and other costs (meals, baggage fees, Uber). The process was very smooth. I had three technical interviews (1:1) on a single day in their offices. Similar to phone screen, except it was on whiteboard. They ask about your motivation and background, and answer your questions at the end. 1. Full coding and algorithms. 2. OOP. More talking and design. I have also written some code for small parts. 3. System design/software decomposition. Much more talking, design and sketching on the whiteboard, almost no coding. All interviewers were very friendly and caring about you. Offices look cool. I liked the culture. They look snob from the outside, I saw that it isn't the case (at least for me). I got contacted after two days. It was not positive. They provided good feedback on my on-site interviews, which is nice. It was a great experience in the end.

Had a chat with HR and then a technical interview with an engineer. They gave some some quite normal leatcode type questions that I had to answer to continue to the next steps.