Zipline Software Engineer Interview Questions
& Process

First up was a 30-minute HR Screen. Then, a take-home test that took about 2-6 hours. After that, we had a 1-hour virtual code review. The onsite consisted of a 30-minute 1:1 with the VP of Engineering (this was pretty free form), followed by a 30-minute behavioral interview with HR. Then, there was a 1-hour session where we had to organize stories based on priority, discussing with a product owner to figure out prioritization and considering company values. We also explored breaking down deliverables into smaller parts, with a comment about choosing larger options vs. smaller ones. Finally, there was a 1-hour backend system design round and a 1-hour frontend component design round, discussing how a user would interact.

This was by far the longest interview process I've ever been through. I felt like I did a lot of consulting work for them, both during the design challenge and the onsite interviews. The whole thing kicked off with a call with the hiring manager to chat about my background and my interest in Zipline, no technical stuff there. Then came the design challenge, which they said would take 2-4 hours, but honestly, that's barely enough time to get through the spec, sketch out a basic design, and maybe start coding. To really do it justice, you'd need way more time. It took me about 2 hours just to nail the algorithm, and then another 8 to code, test, and make it modular and extendable. After that, if your design passed muster, you'd have a design walkthrough with an engineer. You're supposed to talk through your thought process, point out assumptions, highlight your favorite parts, and suggest improvements. I was pretty proud of my design, especially since they mentioned it was beyond their current capabilities (which felt like a red flag). Then a recruiter called to let me know I'd made it to the onsite interviews and went over the schedule and what to expect in each round. The onsite itself had 6 rounds: first, a presentation where I had to talk about my past work to the panel, and they really dug into the technical details, making me feel like a consultant again. Next was an HR round, where I focused on being customer-centric for all the behavioral questions. Then came a Systems Architecture round with two interviewers who seemed a bit inexperienced; I think this might have been where I messed up. The task was to diagram the system and explain my choices. I thought it would be a discussion, but I ended up doing most of the talking and drawing. We finished the design and a few follow-ups, so I felt okay about it. After that, another Systems Design round, but with a smaller scope, focusing on stress testing a component. Again, it felt like consulting as I drew on past experiences and even suggested an improvement to their current system, which the interviewer acknowledged, so I felt good about that one too. Then I had a chat with the cofounder, though I was kept waiting for 10 minutes, which felt disrespectful, but otherwise, it was a casual conversation about the company. Finally, a wrap-up with the hiring manager to discuss the day, potential projects, and my timeline. I left feeling positive and expecting an offer. Two days later, the recruiter emailed to schedule a call about the results. It was a neutral email, and I wasn't sure if it was good or bad news since some companies reject over email and others over a call. I thought I did well, so I was leaning positive. The feedback was that while I had strong intuition and technical skills, they needed someone with end-to-end production architecture experience. Apparently, I asked too many questions in the architecture round and they wanted someone who could design with less guidance, even though I felt the interviewers didn't explain things clearly. They admitted some responsibility during the round, but it didn't seem reflected in the feedback. The interviewers seemed young and new to the company, which might have worked against me. Honestly, I felt misled because my resume clearly showed I lacked that specific experience, and I'd even told the hiring manager. It just didn't make sense that they expected me to suddenly develop that skill during the interview. The recruiter got flustered when I questioned this, so I didn't push it. Oh well, at least I got a trip to SF out of it.

Went through an interview with the hardware test team, which had several rounds, with the last three being quite distinctive. It was designed to assess candidates thoroughly and was very challenging. Everything was pre-scheduled, including the rejection call and other calls. First, a recruiter call, which was a positive conversation where the recruiter expressed enthusiasm for the company and my background. Second, a video call with the hiring manager involved a detailed review of my resume and behavioral questions, which were quite in-depth. Third, a take-home assignment required coding for practical applications, and the time constraint was significant if adhering to the suggested two-hour limit. Candidates have unlimited prep time to strategize. Fourth, a phone call with the recruiter to go over the on-site day schedule, which was very informative. Asking questions during this call is highly recommended. Fifth, a video call featuring a live tour of a facility in Ghana, offering insight into the product's functionality, with the host addressing questions. The subsequent on-site portion (rounds 6-10) included: a portfolio presentation of 'last 3-5 years of work experience' (I presented 2 years) to the hiring manager and potential team members, requiring answers tailored to the role and company culture. The recruiter call in step 4 provided guidance on tailoring experiences. A coding interview involved designing code for a real-life scenario, emphasizing language integration in Zipline's context (like coding for hardware devices). Another round focused on code comprehension, presenting a realistic problem to assess the ability to understand and improve existing functions. A behavioral HR round was particularly unique and challenging, requiring discussion of 'worsts' and lessons learned, alongside standard behavioral queries. Again, questions to the recruiter in step 4, like clarifying the role's IC or leadership nature, are crucial for tailoring responses. A cross-functional interview with an electrical engineer, a first for me, involved debugging a faulty battery using schematics. Despite a simple eventual solution, it took time due to my limited experience in that specific field. Finally, a scheduled rejection call, which was unusual but provided constructive feedback on my performance and lack of experience, though the advance notice caused unnecessary stress. The process was thorough, ensuring a well-rounded hire, but it could be mentally taxing, a fact acknowledged by HR/HM. I felt my skills were demonstrated, but I narrowly missed out due to insufficient experience, which made for a good challenge.