How to ace a System Design interview
System design interviews are daunting. They're open-ended, ambiguous, and often hard to navigate without a clear structure. I outline a simple framework to tackle any system design question with confidence. Whether you're a beginner or brushing up, this framework will have you feeling confident to drive this interview.
Ben Neigher
Staff Software Engineer
System design interviews can be intimidating, but with the right framework, you can approach them with confidence.
The Framework
I've developed a simple 5-step framework that works for any system design question:
- Clarify Requirements: Ask questions to understand the scope
- Estimate Scale: Calculate the numbers that matter
- Design High-Level: Sketch the major components
- Deep Dive: Explore the most critical components
- Identify Trade-offs: Discuss the pros and cons
Step 1: Clarify Requirements
Always start by asking clarifying questions. Don't assume you understand the problem completely.
Step 2: Estimate Scale
Calculate the numbers that will drive your design decisions: users, requests per second, data size, etc.
Step 3: High-Level Design
Sketch out the major components without getting into implementation details.
Step 4: Deep Dive
Choose the most critical or complex component and explore it in detail.
Step 5: Trade-offs
Every design decision has trade-offs. Be prepared to discuss them.