Did the Nike system design round for a senior SWE role (their equivalent of L5, they call it Senior Software Engineer II internally). Sharing my notes.
First thing: Nike isn't running the same gauntlet as FAANG. the system design round is one hour, one interviewer, and they're not trying to watch you sweat through distributed consensus. that said, the caliber is definitely higher than most mid-tier companies.
What I got: design a real-time inventory availability service for nike.com that needs to handle a product drop (think SNKRS app, limited release, 100k concurrent users hitting it in 30 seconds).
Classic product drop question. if you've ever tried to cop a Jordan release you already understand the problem.
What they cared about: how you handle cache invalidation when inventory changes (write-through vs write-behind, they pushed on this) your read vs write ratio assumptions -- i went with something like 50:1 reads to writes during a normal window, much higher during a drop how you prevent overselling without making every request synchronous and slow basic scalability: load balancer, horizontal pod scaling, CDN for static assets
They did NOT go deep on: consensus algorithms, CAP theorem by name (though the concept came up), or anything ML-adjacent.
Format: 5-10 min requirements clarification, ~30 min design, ~15 min deep dive on one component they picked (they picked the cache layer), ~5 min for my questions.
Leveling signal: the interviewer said afterward (rare he did this) that at senior level they want to see you drive the conversation, not wait to be asked. i noticed they were mostly quiet once i started talking, testing whether i'd steer or stall.
If you're at L4 equivalent coming in as senior, brush up on caching patterns and async write approaches. that's the core of what they're testing.