I applied through a recruiter. The process took 2 months.

Overall, the process was very open and transparent. The interviewers were very friendly, and there were no tricky questions. The recruiters were also very open and helpful, answering my questions quickly while passing through the different stages. All the interviews were done online, and I wouldn't say that this impacted my ability to present myself. It all started at the end of October, when I got contacted by one of the talent sourcers. It was a friendly chat where I got asked a bit about me and my experience, the tech stack I'm using, etc. I was given information about the recruiting process and the different stages, and I had the opportunity to ask questions about the company.

Next was the first interview, where I was talking about my experience and, more specifically, a system that I had designed, the decisions, and the trade-offs I made. The interviewer would stop me occasionally to dive deeper into some parts of the system. The questions I got asked were relevant to the project and did not include anything nit-picky or tricky. After passing the first stage, I was given a take-home test to design and implement a system. I used Java to solve it. It took me 5-6 hours to implement the solution and write some unit tests (just the main parts). Then there was a follow-up call with another engineer where I walked them through the implementation. The questions were about the design, some implementation details, and general questions (e.g., concurrency, mutex, etc.).

The final stage consisted of two interviews, done on two different days. But before that, I had a call with the recruiter during which I was given a bit more information about this stage, how to prepare for the behavioral part, and some insights about the levels at Monzo. Then I had the system design interview. It was about designing a system, what services you would have, how it would scale, etc. The conversation was only on this topic with no random questions. After that, I had the behavioral interview. It was talking about your experience, very friendly, and no hypothetical questions were being asked. As I mentioned before, I really liked how transparent everything was, and after receiving the offer, the recruiter gave me information about the teams and feedback from the interviews. I even had the opportunity to talk to one of the directors.

What is a mutex? How do you implement one? There was one answer.

How do you handle failures when processing a message coming from a queue (such as SQS or RabbitMQ)? There was one answer.