The Interview Framework
A repeatable 45-minute plan for a system design interview, with the mistakes that cost candidates the most.
What the interview tests
A system design interview is a conversation about an open-ended problem such as "design a chat app". There is no single correct answer. The interviewer watches for:
- Structure: do you break a vague problem into steps?
- Requirements thinking: do you ask before building?
- Trade-offs: can you say what each choice costs?
- Depth: can you go deep on one or two parts when asked?
- Communication: can they follow you and steer you?
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