System Design interview practice

The classic senior-loop system design interview: requirements, estimation, high-level design, deep dives, and bottleneck defense — spoken out loud.

Topics this interview probes

Requirements & estimation Data modeling Sharding & replication CAP & consistency Caching layers Bottleneck analysis

Design a URL shortener that handles 100k redirects per second. Walk me through your reasoning out loud.
How would you design a news feed with fan-out — push vs pull at different scales?
Defend your sharding strategy: what breaks first as this system grows 100x?

The live interviewer generates fresh, role-tailored questions — and drills down when your answers are vague.