There are multiple phases in the interview process. The first round is a technical test that is done on your own time. After that you will meet with an engineer to discuss the results. The final rounds are a system design interview, followed by an interviewer day at the office. I made it to the system design interview, but was not selected to proceed. Overall a very positive interview process.

Applied online with CV and motivation letter. Did 48-hour Hacker rank test (15 questions - mix of CS fundamentals multi-choice, coding questions (binary tree, recursion) and subjective diagram written section on a hypothetical scenario). Next, had a 30 mins HR call with usual behavioural questions. Next had a 45 min technical interview where I talked through my hacker rank solutions + architecture. questions. After this, I was rejected for tech skills /exp being not good enough. Next stage would have been an assessment day with more challenges/interviews. Everyone was very nice throughout the process and I was given good feedback through a phone call later. Advice: 1. Do your research on the company. Culture fit first is more important than being smart/good at software to Optiver. 2. Be good at coding and know your software architecture, network and hardware fundamentals well (probably need experience for this role despite being advertised to grads) 3. Good Luck!