Skill guide

System Design

Even new-grad loops increasingly include a lightweight system design round: understanding trade-offs matters more than memorizing architectures.

Skill levels

beginner

  • Client-server model, HTTP basics
  • Vertical vs horizontal scaling
  • What a load balancer/cache does

intermediate

  • Databases: SQL vs NoSQL trade-offs
  • Caching strategies
  • Basic message queues

Job-ready

  • Design a system end to end with clear trade-offs (e.g. URL shortener, chat app)
  • Discuss consistency vs availability trade-offs
  • Estimate scale (back-of-envelope math)

How to prove it

  • A completed assessment
  • A written design doc for a project you built
  • A mock system design interview with recorded feedback

Common interview questions

Mentor opinion
  • Design a URL shortener: walk through your approach.
  • How would you scale a service that suddenly gets 100x traffic?
  • SQL or NoSQL for this use case, and why?