Tinder (Walnut Match: S2 Geoshards, Two-Way Ranking, Race-Free Matches, Real-Time Chat)
Tinder system design: build Walnut Match for 2 billion swipes a day with S2 geoshards, reciprocal ranking, race-free matches, real-time chat and safety.
The Engineering Career Operating System
More than interview prep. Your path forks at Senior, into building (IC) or leading (management). Pick a goal, see the real bar, and follow the exact path to get there.
Built by Staff Engineers, Principal Engineers, and Engineering Leaders who've built systems, led teams, and hired engineers.
The bar for each level is the real one, not generic advice.
Two identical gRPC pods sit behind a Kubernetes Service, each with 2 open connections. Pod A serves 9,000 requests per second and pod B serves 900. You add 2 more pods and they get almost no traffic.
Why does pod A get ten times the requests?
Pick one. If it is wrong, you will see why, and you can try again.
Pick a level and be honest. Could you actually answer each of these out loud, right now? If several are shaky, that is the gap, and that is exactly what the path is for.
The bar: Design across services, make and defend trade-offs, and lead a design review.
If several are shaky, you are probably not there yet. Here is the path.
See the Senior Engineer pathWhether you are building LLM systems or getting grilled on them, go deep: the foundations, the engineering, the security, and the AI system design round. Read a full lesson free before you decide.
Now we also crack a few walnuts out loud, on video. Everything here stays right where it is.