Low-level design rounds ask you to turn a prompt like "design a parking lot" into classes, interfaces and working code in about 45 minutes. Eleven foundation modules cover the interview plan, OOP, SOLID (with a deep dive on each principle), design patterns, diagrams and concurrency. Then 15 classic problems are solved end to end, each with a class diagram, an animation or simulator, and code in Python, TypeScript and Java that is compiled and run before it's published.
| Round | The question | Typical prompt |
|---|---|---|
| System design | Which services, databases and queues handle this load? | "Design a URL shortener for 100 million users." |
| Low-level design | Which classes and interfaces, and how do they work together in code? | "Design the classes for a parking lot, and code the core." |
Every problem page has the same ten sections: the prompt, the questions to ask, the classes, how it works, the patterns, the code, concurrency and edge cases, follow-up questions, common mistakes, and a quiz with an extension exercise.
About 45 minutes a day. Read a page, then close it and design the problem yourself on paper with a 45-minute timer before comparing.
| Week | Study | Output by Friday |
|---|