HubSpot Software Engineer interview questions

I came in for final-round interviews in the office and was very impressed with how nice the office was and how awesome all the engineers were. Hubspot feels a bit like a mini silicon-valley in the Boston area. I had four back-to-back interviews with different engineers from Hubspot, each asking different sorts of technical questions. Some involved system-design and some involved database schema/query design.

A recruiter reached out to me and immediately setup a phone interview with a Engineering Manager. He mostly asked questions about my experience and things I've worked on. He dove into some technical details of past projects. The phone interview went well so a few hours later I received an invitation for an on-site interview. The on-site interview consisted of a tour of the offices with the recruiter, followed by 3, one hour long technical interviews, each with one member of the engineering team. The last one was via Google Hangout with one of the Engineers based in Cambridge US office. The technical interviews started with about 10 -15 minutes of chatting about past and current projects, own experience etc and then moved onto technical questions that involved white boarding. The technical questions were really challenging but none of them out of the ordinary. The first round was on algorithms, while the the second and third round was on db & system design but nothing super crazy. Interviewing with HubSpot it can be one of the most enjoyable interviews you will ever have. I would just encourage you to be super collaborative and inquisitive. Your soft skills will be really important, as their team culture is core to their values and figuring out solutions together in small teams is really important. So ask your interviewer questions, and use them like team members and try to work with them on the solution. No one expects you to know everything, it is more your process to figure it out and use your resources. For me that was probably the best part of the interview process, like work with them on the solution, asking questions/second opinion, think out loud. (e.g. Ok, if I go for this approach and use this...I will end up with a nested loop, dependent quadratic complexity O(n2), maybe I should go for a nested linear logarithmic loop and change the inner loop to a divide by 2 and end up with a complexity O(n Log2 n). Bottom line is that all rounds were really interactive and fun, I JUST LOVED IT and I would do it again and again. Working with those guys in a team must be great...Even though I didn't get an offer I was really disappointed as I thought that for my 2+ years of commercial experience as a software engineer I did quite well. So their feedback was: "very positive from a cultural/personality side, but just not strong enough on the tech side". This is why below I will provide you with the full set of questions and my answers. So please prep really well before going into an interview with HubSpot and don't throw away this opportunity, I just loved every minute that I spent there. In other words, you have to do better than what I did, so keep reading below under the Interview questions and good luck.