System Design Interview Guide for Software Engineers

This system design interview guide starts with structure. Clarify requirements, then move through scale, APIs, data models, core components, and operational tradeoffs.

A simple flow

1. Clarify users, use cases, and non-goals.
2. Estimate rough scale and performance needs.
3. Define APIs and data contracts.
4. Sketch the high-level architecture.
5. Discuss storage, caching, queues, and failure modes.
6. Explain tradeoffs and future extensions.

Use this system design interview guide as a rehearsal checklist before a mock interview, then expand each section with the tradeoffs you expect to defend out loud.