Free course
Low-Level Design
Design classes, interactions, and abstractions the way real engineers do in interviews and on the job. Every lesson is a problem with a test suite — pass the tests, then read the AI review to learn what makes the design good.
Free forever · no cohort required
Course contents
OOP Foundations
SOLID Principles
Design Patterns
- 01 Factory pattern — hiding object construction Read →
- 02 Abstract Factory — families of related objects Read →
- 03 Builder — complex objects, readable construction Read →
- 04 Singleton — honestly Read →
- 05 Prototype — clone the template, then tweak Read →
- 06 Adapter — bridging incompatible interfaces Read →
- 07 Facade — simple interface, complex subsystem Read →
- 08 Decorator — behavior wrapping, stacked Read →
- 09 Proxy — stand-in with a purpose Read →
- 10 Composite — trees where leaves and containers share an interface Read →
- 11 Strategy — swappable algorithms Read →
- 12 Observer — publish, subscribe, react Read →
- 13 Command — actions as first-class objects Read →
- 14 State — behavior varies with internal state Read →
LLD Problems
- 01 LLD problem — Vending Machine Read →
- 02 LLD problem — Parking Lot Read →
- 03 LLD problem — Tic-Tac-Toe Read →
- 04 LLD problem — Snake and Ladder Read →
- 05 LLD problem — Elevator Read →
- 06 LLD problem — Splitwise Read →
- 07 LLD problem — Movie Booking (BookMyShow-style) Read →
- 08 LLD problem — LRU Cache Read →
- 09 LLD problem — Rate Limiter Read →
- 10 LLD problem — File System Read →
- 11 LLD problem — Chess (piece movement) Read →
- 12 LLD problem — Ride Matching (Uber-style) Read →