I interviewed at Square for a senior product designer role on their Commerce products team. Made it to offer but turned it down for another role. Want to share the design interview specifics because they're genuinely different from a typical product design loop.
Overall structure: Recruiter screen (25 min) Portfolio review with hiring manager (60 min) Design exercise take-home (1 week) Design critique: you present the take-home to 3 designers + PM (60 min) Cross-functional partnership round (with a PM and an EM, 45 min) Behavioral round (45 min)
The portfolio review isn't a passive 'walk me through your work.' The interviewer digs in hard on decisions. 'Why this layout and not that one.' 'What did you cut and why.' 'How did you measure whether this design worked.' If you have case studies that are primarily visual showpieces without process, that's going to be a problem here. They want the thinking, the iteration, the failure.
The take-home was interesting. I was given a scenario about a small business owner trying to understand their weekly sales performance from a Square Dashboard. The ask was to redesign a specific section for clarity and actionability. It was open-ended. I spent about 6 hours on it, did a quick competitive audit, made explicit design system choices (they use a fairly opinionated design language internally), and framed my decisions around merchant context, not just aesthetics.
The critique presentation is where people visibly sink or swim. Three designers, a PM. The PM asked how I would measure success for my proposed redesign. One of the senior designers asked me to defend a specific typographic choice. It got specific fast. If you can't articulate your rationale under pressure you'll notice it in the debrief.
The cross-functional round tested how I communicate design tradeoffs to non-designers. The PM asked how I'd respond if engineering said my proposed layout would take 3x the sprint capacity. Good question. Have a real answer.
Overall: Square design interviews are among the more rigorous mid-size-company loops I've been through. They're building real products for real merchants and they want designers who can defend decisions under scrutiny.