System Design Interview Practice
System design interviews evaluate your ability to architect scalable, reliable systems from requirements to implementation. You are expected to gather requirements, estimate capacity, choose appropriate technologies, design data flows, and identify failure modes. These rounds are standard for senior engineering roles and increasingly common for mid-level positions at tech companies.
What to Expect
- Open-ended prompts like "Design a URL shortener" or "Design a real-time chat system"
- Expectation to gather requirements before proposing architecture
- Capacity estimation with back-of-envelope calculations
- Component-by-component deep dives on data stores, caching, and compute
- Questions about failure modes, monitoring, and operational concerns
Tips for Success
- 1Always start with requirements. Ask about scale (users, requests per second), latency targets, consistency requirements, and durability needs before drawing anything.
- 2Do back-of-envelope capacity math out loud. Estimate storage, bandwidth, and compute needs. Even rough numbers show you think quantitatively about systems.
- 3Design for failure. For every component you propose, explain what happens when it goes down and how the system recovers. Single points of failure are red flags.
- 4Explain your technology choices with tradeoffs. "I chose PostgreSQL over DynamoDB here because we need strong consistency for financial transactions" shows reasoning.
- 5Cover operational concerns: monitoring, alerting, deployment strategy, and how you would debug issues in production. These signal engineering maturity.
AI Interviewers
Each practice session pairs you with one of three AI interviewers, each with a distinct personality and questioning style.
E
Emma
Analytical & Supportive
M
Max
Strict & Direct
D
David
Technical & Precise
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