What is a System Design Interview?
System design interviews test your ability to design large-scale distributed systems. Unlike coding interviews, there's rarely one correct answer — the goal is to demonstrate structured thinking, knowledge of trade-offs, and communication skills.
The 6 Scoring Categories
On LeetDesign, your answer is scored across six dimensions:
- Requirements — Did you clarify functional and non-functional requirements before diving in?
- Capacity — Did you estimate traffic, storage, and bandwidth?
- High-Level Design — Is your architecture diagram clear and correct?
- Deep Dive — Did you go deep on the most critical components?
- Trade-offs — Did you compare alternatives and justify your choices?
- Failure Modes — Did you consider how the system fails and how to recover?
A Simple Framework
- Clarify requirements (5 min)
- Estimate scale (5 min)
- Draw high-level diagram (10 min)
- Deep dive into 2-3 components (15 min)
- Discuss trade-offs and failure modes (5 min)
Start practicing with the problems on LeetDesign.