o9 Solutions Senior Software Developer interview questions

Got a hackerrank test with 20 questions. It had a lot of topics. I was interviewing with the WebApi team. First round was with an SSE. Questions around c#, advanced level, SQL, DSA. Most questions were trick questions but fun. He was mostly respectful and by the end, it felt like he respects my knowledge in C#, microservices etc. We talked like we are already team members. Second round was a terrible experience. The interviewer joined late and had his camera off. It was with a software architect of same WebApi team. He went through my github and asked me to find 5 mistakes in a piece of code I had written for my personal project. Then he said he could only find 3 mistakes, so I can tell 3 mistakes. Then he proceeded to only point out 1 mistake which wasn't even a mistake because it was not a production code. Then he started teaching me how to register a HttpClientFactory, and said that I did not implement it. I had it in my code but he just could not analyse the code properly because it was built on DDD model. This itself showed me the negative attitude he has and that he suffers from a superiority complex. He was not taking interview to check my skills but instead to belittle me and prove how he knows more. He wasted so much time on this antics. I should have ended the interview here politely thanking him which is a thought that crossed my mind. For some reason, I did not and regretted it later. One question itself would take 10 minutes for him to ask. He would say unnecessary things to show how great he is and I kept waiting for when he would actually state the question he wants to ask. I hated every minute of this interaction but remained respectful, in suffocation. He opened notepad in his screen and asked me how to test a service code which does not have interface. Took 15 minutes to just ask this and there was no purpose behind it because it is anyway a bad approach. Then he opened visual studio and asked me to recite a LINQ statement while he types. What kind of interview was this? He thinks people code like this, is this a VIVA? Then he again took 15 minutes to ask a basic question around distributed transactions. When I gave right answers, he belittled me. I gave another approach, he again spoke rudely. Then he made an unnecessary remark saying that I would never develop a fault tolerant system. I later checked and my answers were correct. It was 2 phase commit which I spoke about. I don't know what was on his mind. We had 3 minutes left and he asked if I have any questions. I was really exhausted by him and decided to end my suffering and told him that I have no questions. I would not choose to speak with such a person voluntarily. Outcome : Of course, he gave me a negative feedback. But recruiter never communicated it to me. Before this, recruiter would call me multiple times to schedule interviews. Later, after 10 days, I called recruiter myself and she simply said I did not clear second round and gave no other feedback. It is a shame that a toxic employee with no interview experience is given the responsibility to hire candidates. The first interviewer asked some tough questions and tried to make me self doubt my answers but he remained respectful. I also have the relevant experience of working at the problem they are solving but apparently, they are not looking for good engineers but someone who can work with toxic architects. One major take way is to end interviews where interviewer is being disrespectful just because they are on that side of the table. It is a nightmare working with such people anyway.

I interviewed for a Senior Engineer backend position in Platform team at O9. All interviews were remote. Round 1 - Online Assessment - 2 medium LC problems around Stacks/Queues and logic. Pass with 17/20 test cases. Round 2 - Technical Interview 1 - Initially the interviewer asked questions on projects. Then asked a few easy/medium coding questions and later started with system design on a big data/multithreading problem. Problem revolved around using all the cores of a CPU to handle an infinite data stream. Interviewer was calm and gave enough time to think. Solved 90% of the problems in this round. Verdict - Pass. Round 3 - Technical Interview 2 - Same as round 1 with questions on building large scale systems. Wanted to know all that I have worked with and how I have dealt with day to day problems. Was not asked to code anything. Interviewer was calm and helpful. Verdict - Pass. Round 4 - Hiring Manager Round - Started with my latest projects. Then asked many questions around Computer science fundamentals, hashing techniques (how do we achieve O(1) etc), graphs, multithreading (mutex/semaphore). Then asked me to write a program which had a tweaked Binary search. Threw some more questions around the complexity and then concluded the interview. HM was intelligent and gave hints whenever required. Answered 90% of the questions. Verdict - Pass. Round 5 - HR - This is where things get interesting. The HR was rude, and continuously questioned my company switches. For 45 minutes he had this unwelcoming facial expression like he has come with a mindset to reject me, not hire me. Answered all his queries politely but he came to that point only, again and again. I wonder, they knew about this right from the very beginning but still they waited for 5 rounds to have this discussion. Asked some general behavioural and team building questions which I answered. After ghosting for 8 days, they communicated that I have been rejected. Final Verdict - Reject. It was such a waste of time and energy. Not recommened.