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How do I learn system design as a junior developer?

Team FAQ: this question comes up often, so we've answered it below. Add your own experience, or a different view, in the comments.

System design seems senior-only. How can a junior start building this skill?

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devlk Team·

Start with the systems you already work on, then learn the core building blocks step by step.

  1. Understand your current system: draw how a request flows through your company's application, from client to load balancer to servers, database, cache and queues. Ask seniors to explain the parts you don't understand.
  2. Learn the building blocks one at a time:
    • HTTP, DNS and load balancers
    • Databases: indexes, SQL vs NoSQL, replication
    • Caching and when to use it
    • Message queues and background jobs
    • CDNs, rate limiting, consistency
  3. Read real architectures: many companies publish engineering blog posts explaining how they built and scaled their systems.
  4. Practise classic problems (a URL shortener, a chat app) using a framework: requirements, estimates, API, data model, design, trade-offs.
  5. Join design discussions at work: read design documents and ask why decisions were made.

The free System Design Primer is a good structured resource, and our beginner's framework for system design interviews shows how to put it together in an interview.

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