Overall, a very positive experience. I find the reviews on here that say the interview was 100% negative hard to believe. At the very least, everyone I interacted with was professional, and nearly all of them were outright friendly. I obviously can't predict what questions others will be asked during their interviews, but in general, Square doesn't seem to ask "hard" questions that rely on figuring out a specific trick to get the correct answer. Instead, they ask what I'd call "fair" questions - multistage OOP problems that incorporate CS fundamentals to varying extents. That being said, if people study in a way that heavily favors trick problems, they might find Square's more practical/applied questions pretty hard. Biggest piece of advice: get your code running. I think the most important difference from many other companies is that you're actually coding on a computer, not whiteboarding - so your code has to run. Getting your code to run should be your first priority. If it doesn't run, you need to be able to debug and fix your errors quickly. Get to a working solution for the initial stage of the question, run some test cases, refactor... then repeat for the next, harder stage of the question. Honestly, most of my coding interviews at Square ended up being kind of fun. You may or may not get asked specific time/space complexity questions about your code, depending on the interviewer. Interviewers were all friendly, and helped unblock me if I got too stuck for too long. They kept things moving. The post-interview experience was very positive, too. Things moved quickly - I heard back within a couple days - and the team selection, offer, and negotiation all went pretty smoothly. End-to-end, the entire process from initial phone screen to final offer took 4 weeks, and could have moved faster if my personal schedule had permitted it.