Low Level Design
Design better code.
Build with purpose.
Learn how to translate requirements into clean, maintainable object-oriented designs. Explore core concepts, design patterns, practical problem-solving, and the decisions behind extensible software.
Your learning path
Learn LLD step by step.
Build your understanding from object-oriented fundamentals to practical design decisions and complete design problems.
Object-Oriented Programming
Understand encapsulation, abstraction, inheritance, and polymorphism—the building blocks of object-oriented code.
Learn OOPObject-Oriented Design
Learn to assign responsibilities, model relationships, and turn requirements into meaningful classes and objects.
Explore OODClean Code
Improve naming, readability, separation of responsibilities, and the ease of changing and testing your code.
Explore clean codeAPI Design
Learn to design clear and consistent APIs, define endpoints, structure requests and responses, and handle errors effectively.
Explore API designDatabase Design
Learn to model entities and relationships, choose appropriate tables and keys, and design schemas that support application needs.
Explore database designDesign Patterns
Recognize recurring design problems and learn when established patterns help—and when simpler code is enough.
Learn design patternsLayered Architecture
Understand how responsibilities can be separated into layers to organize application code and dependencies.
Explore architectureLLD Problems
Apply your knowledge to practical design exercises. Refine your models, discuss trade-offs, and improve your solutions.
Practice LLD problemsExplore the fundamentals
Understand the building blocks.
Select a concept to explore the role it plays in designing maintainable object-oriented software.
Model the domain, not just the data.
Classes define state and behaviour; objects are their runtime instances. A good design models meaningful domain concepts and gives each object a clear purpose.
Start by identifying the important entities and what each one needs to know or do. Avoid creating classes that merely duplicate data without a clear responsibility.
Give every class a clear reason to exist.
Decide which object owns each piece of state and behaviour. Keep related responsibilities together and avoid making one class responsible for unrelated parts of the system.
Consider how a change in requirements will affect your design. Clear responsibilities make code easier to understand, test, and extend.
Make change easier, not harder.
Design principles help you reason about coupling, cohesion, abstraction, and dependencies. They guide decisions that make software easier to modify without unnecessary changes across the system.
Apply principles to a real requirement or design problem. They are tools for making trade-offs, not rules that require adding abstractions everywhere.
Use patterns when the problem calls for them.
Design patterns describe reusable approaches to recurring design problems. They help communicate intent and can make object relationships easier to understand.
First understand the requirement and the constraints. Then decide whether a pattern solves a real problem better than a straightforward implementation.
A practical workflow
From requirements to design.
Use a consistent process to reason through an LLD problem before jumping into classes or code.
Clarify requirements
Identify core use cases, constraints, assumptions, and what the system must support.
Identify objects
Find the key domain entities, their state, behaviour, and responsibilities.
Define relationships
Establish associations, ownership, interfaces, and the way objects collaborate.
Validate and refine
Walk through use cases, address edge cases, and improve the design where needed.
Put knowledge into practice
Good design comes from solving problems.
Move beyond definitions. Work through design problems, explain your decisions, examine alternatives, and learn how to build solutions that can evolve with requirements.
Build your design skills
Think clearly. Design thoughtfully. Write better code.
Start with the fundamentals, follow a structured approach, and apply what you learn to practical Low-Level Design problems.