BeenThere

After conducting 200+ system design interviews at top tech companies, here's what separates great candidates from good ones:

Start with Requirements Clarification

Never jump straight into drawing boxes and arrows. The first 10 minutes should be spent understanding the problem deeply. Ask about scale, users, features, and constraints.

Think in Layers

Break down your system into logical layers: presentation, application, data, and infrastructure. This shows structured thinking and makes complex systems manageable.

Scale Gradually

Start with a simple solution that works, then scale it step by step. Don't over-engineer from the beginning. Show how you'd handle 1K users, then 1M, then 100M.

Know Your Numbers

Memorize key performance numbers: database read/write speeds, network latency, storage costs. These help you make informed decisions during the interview.

Trade-offs Are Key

Every design decision has trade-offs. Explicitly discuss them: consistency vs availability, cost vs performance, complexity vs maintainability.

Real-World Experience Matters

Reference actual technologies and patterns you've used. Mention specific databases, caching strategies, and monitoring tools. This shows practical experience.