Did the Block final round in January 2026 for a senior backend role in the Square financial infrastructure team. Remote onsite, Zoom, 5 rounds across one day. Here's how the day actually broke down.
Round 1: Coding (45 min). One medium-hard algorithm problem. Mine was interval scheduling with some added constraints. Wrote it in Python, got a clean working solution about 30 min in, spent the last 15 talking through complexity and edge cases. Interviewer was a senior SWE, calm, not adversarial.
Round 2: System Design (60 min). Already posted about this elsewhere but: payments-domain problem, idempotency and consistency were the main themes. Gave me a distributed systems problem that was clearly shaped by real Block infrastructure.
Round 3: Behavioral (45 min). Dedicated behavioral round with what seemed like an EM or senior IC. Covered 4-5 questions fully. See my notes on the behavioral round separately.
Round 4: Hiring Manager (45 min). Half behavioral, half 'let's talk about what you'd be working on.' They walked me through the actual project space, the team structure, current technical challenges. This is also where comp expectations came up again briefly.
Round 5: Cross-functional or skip-level (30 min). For me this was a 30-minute conversation with a PM who I'd be working closely with. They asked about how I think about product-engineering collaboration, nothing too deep technically.
Debrief moved pretty fast. I got a recruiter call 4 business days after the final round with a verbal offer. The written offer came 2 days after that. Total process from first recruiter email to signed offer was 6 weeks.
One thing I appreciated: feedback from the hiring manager on the call. They actually told me which rounds went well and where I was borderline. Rare.