This roadmap is built for software engineers preparing for LLD interviews at top-tier product companies like MAANG (Meta, Amazon, Apple, Netflix, Google) and other tech giants (Uber, Flipkart, etc.). It covers all the essential topics, patterns, and subtopics with a focus on hands-on system design and coding skills.
✅ Phase 1: OOPs & Design Principles (Foundational)
Learn how to write clean, extensible, and maintainable code.
Object-Oriented Programming (OOP)
- Classes & Objects
- Inheritance, Polymorphism, Encapsulation, Abstraction
- Composition vs Inheritance
- Aggregation vs Association
- Constructor chaining
SOLID Principles
- Single Responsibility Principle (SRP)
- Open/Closed Principle (OCP)
- Liskov Substitution Principle (LSP)
- Interface Segregation Principle (ISP)
- Dependency Inversion Principle (DIP)
Other Core Principles
- DRY (Don’t Repeat Yourself)
- YAGNI (You Aren’t Gonna Need It)
- KISS (Keep It Simple, Stupid)
- Law of Demeter
✅ Phase 2: Design Patterns (Classic & GoF)
Understand and apply reusable design patterns in interviews and real-world projects.
Creational Patterns
- Singleton (Thread-safe, Lazy/Eager Initialization)
- Factory Method
- Abstract Factory
- Builder
- Prototype
Structural Patterns
- Adapter
- Decorator
- Proxy (Static & Dynamic)
- Facade
- Composite
- Flyweight
Behavioral Patterns
- Strategy
- Observer
- Command
- State
- Template Method
- Chain of Responsibility
- Mediator
- Iterator
- Memento
✅ Phase 3: Hands-on Design Practice (Object Modeling)
Learn how to model real-world problems in code using OOPs + Design Patterns.
Must-Practice Real-World LLD Problems
- Design a Parking Lot
- Design an Elevator System
- Design a Tic-Tac-Toe / Chess Game
- Design a Movie Ticket Booking System
- Design a Cab Booking System (Uber)
- Design a Hotel Management System
- Design an ATM
- Design a Library Management System
- Design a Splitwise App
- Design a File System (Folder Structure)
- Design Snake and Ladder / Ludo
- Design Notification System (Email/SMS/Push)
What to Practice in Each Design:
- Identify core entities and relationships
- Apply correct design principles (SRP, OCP)
- Choose and apply right design patterns
- Handle concurrency & multithreading where required
- Discuss scalability and extensibility
- Interface vs abstract class usage
✅ Phase 4: Advanced Concepts for MAANG
Deep dive into architecture and scalable components to impress interviewers.
Concurrency & Multithreading
- Thread-safe Singleton
- Producer-Consumer
- BlockingQueue, ThreadPool
- Locks, Semaphores
- Event-driven architecture (Observer)
Best Practices
- UML Diagrams (Class, Sequence, Activity)
- Testability of components
- Handling large data sets in memory (pagination, caching)
- Extensible plugin-based architecture
Principles to Keep in Mind
- Favor composition over inheritance
- Program to interface, not implementation
- Interface segregation
- Fail fast and recover gracefully
🛠️ Tools & Practice Platforms
- UML Tools: Lucidchart, draw.io, Creately
- Practice: InterviewBit, DesignGurus, LowLevelDesign.io, GitHub repos
- Mock Interviews: Pramp, Exponent, peers
🧪 How to Practice LLD Interviews
- Choose a design problem
- Draw class diagram (entity modeling)
- Write class skeletons with methods
- Identify design patterns if applicable
- Add validations, edge cases
- Discuss improvements, scalability
🎯 Final Advice for MAANG LLD Success
- Always start with requirements & assumptions
- Focus on extensibility, not overengineering
- Communicate while designing; it’s a discussion
- Think in layers: controller → service → model → data
- Read open-source Spring projects or Java repositories to see real-world architecture
💡 Consistency in practicing 1–2 LLD problems per week for 2–3 months will significantly improve your chances of cracking MAANG-level design rounds.
