Complete System Design(LLD) Course 2026 | LLD Masterclass | Beginner to Advanced | Hindi + English

If you want to **master Low Level Design (LLD) from scratch and learn how real-world systems are designed**, this is the complete course you need.

This is not just a Design Patterns course.

This is a **12+ hour deep dive into Low Level Design**, starting from the absolute fundamentals and gradually taking you all the way to designing **real-world, interview-level and production-oriented systems**.

We start with the most basic question:

**What is LLD? Why do we need LLD? What happens when we don't follow good design principles?**

Then we build everything step-by-step.

## 🚀 What You'll Learn

### 1. Low Level Design Fundamentals

* What is Low Level Design?
* Why do we need LLD?
* LLD vs HLD
* What happens when there is no proper LLD?
* How good design helps in real-world software development
* How to approach an LLD problem

### 2. OOPs — The Foundation of LLD

* Classes & Objects
* Encapsulation
* Abstraction
* Inheritance
* Polymorphism
* Composition
* Association
* Aggregation
* Real-world examples

### 3. UML Diagrams

* Class Diagrams
* Relationships between classes
* Association
* Aggregation
* Composition
* Inheritance
* Dependency
* How to convert requirements into UML

### 4. SOLID Principles

Learn every SOLID principle with practical examples:

* Single Responsibility Principle
* Open/Closed Principle
* Liskov Substitution Principle
* Interface Segregation Principle
* Dependency Inversion Principle

More importantly, we'll understand **WHEN and WHY** these principles actually matter in real projects.

### 5. Design Patterns

A deep dive into commonly used Design Patterns with:

* What problem does the pattern solve?
* Why do we need it?
* Real-world examples
* When should you use it?
* When should you NOT use it?
* How it appears in real software systems
* Practical implementation

And the best part:

**The Design Patterns are implemented using Node.js as well**, so you can understand how these concepts translate into a modern backend development environment.

### 6. Real-World LLD of Giant Systems 🔥

We don't stop at theory.

We take everything we've learned and apply it to **real-world systems**, including systems inspired by platforms such as:

* Uber
* Swiggy
* And other large-scale applications

You'll learn how to identify entities, responsibilities, relationships, interfaces, abstractions and design patterns while converting requirements into an actual LLD.

### 7. C++ / Java → Node.js

This is one of the most important parts of the course for working professionals.

A lot of LLD resources demonstrate everything in **Java or C++**.

But what if your company's tech stack is **Node.js / JavaScript / TypeScript**?

Should you completely ignore LLD?

**Absolutely not.**

We first understand and implement the LLD concepts in languages commonly used for LLD interviews such as **C++ / Java**, and then take the same designs and implement them using **Node.js**.

This helps you understand something extremely important:

**LLD is about design principles, not about a particular programming language.**

Once you understand the design, you should be able to implement it in the language used by your team.

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## 🎯 Who Is This Course For?

This course is for:

* Software Engineers
* Backend Developers
* Full Stack Developers
* SDE-1 / SDE-2 developers
* Developers preparing for LLD interviews
* Developers preparing for Machine Coding rounds
* Developers preparing for Object-Oriented Design interviews
* Students learning Software Design
* Developers working with JavaScript / Node.js
* Developers who know OOP but struggle with LLD
* Anyone who wants to understand how real-world software is designed

Whether you're preparing for interviews or trying to write **clean, maintainable and scalable code in your day-to-day job**, this course is designed to take you from fundamentals to practical implementation.

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## ⏱️ CHAPTERS

00:00 - 44:36 - Introduction to LLD
44:37 - 01:28:44 - OOPs Fundamentals : Abstraction & Encapsulation
01:28:45 - 01:56:03 - OOPs Fundamentals : Inheritance & Polymorphism
01:56:04 - 03:10:26 - UML Diagrams : Class Diagram & Sequence Diagram
03:10:27 - 05:08:45 - SOLID Principles
05:08:46 - 12:13:56 - Design Patterns : Real-World Examples and use-cases in Real-Projects

Stay tuned for PART-2

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## 🔥 If you found this course useful

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And tell me in the comments:

**Which real-world system should we design next?**

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