System Design Interview Questions
6 classic system design problems with structured approaches, key components, and trade-off discussions.
System Design Interview Framework
Ask about scale, features, and constraints. Don't assume—different scales need different designs.
Draw the main components and data flow. Keep it simple—details come later.
Pick 2-3 components to detail. Discuss data models, APIs, and algorithms.
Discuss alternatives and their trade-offs. Show you understand there's no perfect solution.
Common System Design Mistakes
Jumping to Solutions
Don't start drawing boxes before understanding the problem. A URL shortener for 100 users is completely different from one for 100 million users.
Over-engineering
Not every system needs Kafka, Kubernetes, and machine learning. Design for the scale you're given, not the scale you imagine. Mention how you'd evolve the design if scale increases.
Ignoring Trade-offs
Every design decision has downsides. If you don't mention them, the interviewer will think you don't know them. Proactively discuss what you're trading off.
Going Silent
System design is collaborative. Think out loud. If you're stuck, say so and explain what you're considering. The interviewer may give hints if you're communicating well.
Practice Makes Progress
System design is a skill that improves with practice. Mock interviews with feedback help you identify gaps in your explanations and reasoning.