Low-Level Design (LLD) Roadmap

April 28th 2025

Low-Level Design (LLD) Roadmap

Low-Level Design (LLD) focuses on designing the internal structure of a system, including classes, methods, and interactions. This roadmap will guide you through the essential concepts and skills required to master LLD.

1. Prerequisites

Programming Fundamentals
- Master at least one programming language (e.g., Java, Python, C++).
- Understand Object-Oriented Programming (OOP) concepts:
  - Classes and Objects
  - Inheritance
  - Polymorphism
  - Encapsulation
Data Structures and Algorithms
- Arrays, Linked Lists, Stacks, Queues
- Trees, Graphs, HashMaps
- Sorting and Searching algorithms

2. Core LLD Concepts

Object-Oriented Design (OOD) Principles
- SOLID Principles:
  - Single Responsibility Principle
  - Open/Closed Principle
  - Liskov Substitution Principle
  - Interface Segregation Principle
  - Dependency Inversion Principle
- DRY (Don't Repeat Yourself)
- KISS (Keep It Simple, Stupid)
- YAGNI (You Aren't Gonna Need It)
Design Patterns
- Creational Patterns:
  - Singleton
  - Factory
  - Builder
- Structural Patterns:
  - Adapter
  - Composite
  - Proxy
- Behavioral Patterns:
  - Strategy
  - Observer
  - Command

3. System Design Basics

Understanding Requirements
- Functional vs Non-Functional Requirements
- Use Case Diagrams
Class Diagrams
- UML Basics
- Relationships: Association, Aggregation, Composition
Sequence Diagrams
- Interaction between objects over time

4. Hands-On Practice

Design Real-World Systems
- Design a Parking Lot System
- Design an Online Bookstore
- Design a Food Delivery System
Code Implementation
- Translate designs into working code.
- Focus on clean, modular, and testable code.

5. Advanced Topics

Concurrency and Multithreading
- Thread Safety
- Deadlocks and Race Conditions
Scalability Considerations
- Caching
- Database Design
Design for Maintainability
- Code Reviews
- Refactoring Techniques

6. Resources

Books
- "Design Patterns: Elements of Reusable Object-Oriented Software" by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides
- "Clean Code" by Robert C. Martin
- "Head First Design Patterns" by Eric Freeman and Elisabeth Robson
Online Courses
- System Design Primer (GitHub)
- Low-Level Design on Educative.io
Practice Platforms
- LeetCode
- HackerRank
- GeeksforGeeks

7. Tips for Success

Start with small projects and gradually increase complexity.
Collaborate with peers to review and improve designs.
Stay updated with industry trends and best practices.

By following this roadmap, you can build a strong foundation in Low-Level Design and apply these skills to real-world software development projects.