The interview round between LeetCode and the whiteboard: model a real system in classes, or build a systems primitive from scratch — then defend it when the requirements change. Machine coding and systems programming, taught the way interviewers grade them.
22 chapters · 111 lessons · free-preview lessons open without an account
What an LLD round actually measures, in both its flavors — and how to convert design knowledge into interview signal: requirements gathering, design-in-words, principles demonstrated rather than recited, and surviving the mid-interview twist.
The object-design flavor of LLD: parking lots, caches, rate limiters, Splitwise. Each chapter works one interview problem end to end — the requirements conversation, the model in words, the implementation, and the design space around it.
The low-level flavor of LLD: allocators, ring buffers, thread pools, locks. Memory layout, invariants, and concurrency — worked as interview problems, with the reasoning that survives an interviewer's pressure.
