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Grokking the Low Level Design Interview Using OOD Principles

A battle-tested guide to object-oriented design interviews—developed by FAANG engineers. Master OOD fundamentals and practice real-world interview questions.

4.6
215 Lessons
19 Mock Interviews
70h
Updated 1 month ago
Join 2.9 million developers at
Join 2.9 million developers at
LEARNING OBJECTIVES
  • Apply OOP fundamentals, including encapsulation, abstraction, inheritance, and polymorphism, to real design problems
  • Use SOLID principles and common design patterns (creational, structural, behavioral) to write clean, maintainable systems
  • Break down open-ended OOD interview problems into requirements, components, and interactions using a bottom-up approach
  • Design class, use case, sequence, and activity diagrams for 20+ real-world systems (parking lots, elevators, Amazon, LinkedIn, and more)
  • Implement complete solutions in Java, Python, C++, C#, or JavaScript
  • Practice with 19 mock interviews simulating real-world FAANG OOD rounds
Why choose this course?

Learn to think like a Software Architect

Top engineers stand out because they can design scalable, maintainable systems, not just write code. Mastering object-oriented design principles and design (LLD) concepts helps you think like an architect and build software that lasts.

Strengthen your OOD fundamentals

Build a solid foundation with key object-oriented concepts such as encapsulation, abstraction, inheritance, and polymorphism.

Design real-world systems step by step

Start with classic case studies like Parking Lot and Library Management to practice defining system requirements and creating use case, class, sequence, and activity diagrams.

Put your skills to the test

At the end of each case study, put your knowledge into action through an interactive mock interview.

Learning Roadmap

215 Lessons28 Quizzes

1.

Introduction

Introduction

This chapter introduces the course, including its prerequisites, structure, strengths, and the target audience.

2.

Cornerstones of Object-Oriented Programming

Cornerstones of Object-Oriented Programming

This chapter covers the background of OOP, focusing on encapsulation, abstraction, inheritance, and polymorphism, ending with a quiz on basics.

3.

Object-Oriented Design

Object-Oriented Design

8 Lessons

8 Lessons

This chapter explores how to conduct object-oriented analysis and design using UML, covering various diagrams like use case, class, sequence, and activity.

4.

Object-Oriented Design Principles

Object-Oriented Design Principles

7 Lessons

7 Lessons

This chapter covers the SOLID design principles: Single Responsibility, Open Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion.

5.

Design Patterns

Design Patterns

7 Lessons

7 Lessons

This chapter teaches you about the classification of design patterns, including creational, structural, and behavioral patterns, followed by a quiz.

7.

Designing a Parking Lot

Designing a Parking Lot

9 Lessons

9 Lessons

This chapter covers the design of a parking lot system, including requirements, UML diagrams, and implementation code to illustrate practical application.

8.

Designing an Elevator System

Designing an Elevator System

9 Lessons

9 Lessons

This chapter shows the design of an elevator system, detailing the requirements, use case, class, sequence, and activity diagrams, and the implementation code.

9.

Designing a Library Management System

Designing a Library Management System

9 Lessons

9 Lessons

This chapter teaches you the design of a library management system with requirements, use case, class, sequence, activity diagrams, and implementation code.

10.

Designing the Amazon Locker Service

Designing the Amazon Locker Service

9 Lessons

9 Lessons

This chapter covers the design of the Amazon Locker Service, focusing on requirements, UML diagrams, and implementation code to create a complete system.

11.

Designing a Vending Machine

Designing a Vending Machine

8 Lessons

8 Lessons

In this chapter, you will learn the design of a vending machine, including requirements, use case, class, activity diagrams, and implementation code.

12.

Designing an Online Blackjack Game

Designing an Online Blackjack Game

8 Lessons

8 Lessons

This chapter explores how to design an online blackjack game, covering requirements, use case, class, activity diagrams, and implementation code.

13.

Designing a Meeting Scheduler

Designing a Meeting Scheduler

9 Lessons

9 Lessons

This chapter shows the design of a meeting scheduler system, detailing the requirements, UML diagrams, and implementation code for the complete design.

14.

Designing a Movie Ticket Booking System

Designing a Movie Ticket Booking System

9 Lessons

9 Lessons

This chapter covers the design of a movie ticket booking system, including requirements, UML diagrams, and implementation code to build the system.

15.

Designing a Car Rental System

Designing a Car Rental System

9 Lessons

9 Lessons

This chapter teaches you the design of a car rental system, detailing requirements, UML diagrams, and implementation code for a functional system.

16.

Designing ATM

Designing ATM

9 Lessons

9 Lessons

In this chapter, you will discover the design of an ATM system, focusing on requirements, use case, class, sequence, activity diagrams, and implementation code.

17.

Designing a Chess Game

Designing a Chess Game

8 Lessons

8 Lessons

This chapter shows the design of a chess game, including requirements, use case, class, activity diagrams, and implementation code to develop the game.

18.

Designing a Hotel Management System

Designing a Hotel Management System

9 Lessons

9 Lessons

This chapter covers the design of a hotel management system, detailing the requirements, UML diagrams, and implementation code for a complete system.

19.

Designing the Amazon Online Shopping System

Designing the Amazon Online Shopping System

9 Lessons

9 Lessons

This chapter teaches you the design of the Amazon online shopping system, focusing on requirements, UML diagrams, and implementation code.

20.

Designing Stack Overflow

Designing Stack Overflow

9 Lessons

9 Lessons

In this chapter, you will learn the design of Stack Overflow, including requirements, use case, class, sequence, activity diagrams, and implementation code.

21.

Designing a Restaurant Management System

Designing a Restaurant Management System

9 Lessons

9 Lessons

This chapter explores how to design a restaurant management system, covering requirements, UML diagrams, and implementation code for the system.

22.

Designing Facebook

Designing Facebook

9 Lessons

9 Lessons

This chapter shows the design of the Facebook system, detailing requirements, use case, class, sequence, activity diagrams, and implementation code.

23.

Designing an Online Stock Brokerage System

Designing an Online Stock Brokerage System

9 Lessons

9 Lessons

This chapter covers the design of an online stock brokerage system, including requirements, UML diagrams, and implementation code.

24.

Designing a Jigsaw Puzzle

Designing a Jigsaw Puzzle

4 Lessons

4 Lessons

In this chapter, you will discover the design of a jigsaw puzzle, focusing on requirements, class diagram, and implementation code for the puzzle.

25.

Designing an Airline Management System

Designing an Airline Management System

9 Lessons

9 Lessons

This chapter shows the design of an airline management system, detailing the requirements, UML diagrams, and implementation code for the system.

26.

Designing ESPNcricinfo

Designing ESPNcricinfo

9 Lessons

9 Lessons

This chapter covers the design of the ESPNcricinfo system, including requirements, use case, class, sequence, activity diagrams, and implementation code.

27.

Designing LinkedIn

Designing LinkedIn

9 Lessons

9 Lessons

This chapter explores how to design the LinkedIn system, covering requirements, UML diagrams, and implementation code for a complete design.

28.

Wrapping Up

Wrapping Up

2 Lessons

2 Lessons

This chapter concludes the course with valuable tips for excelling in object-oriented design interviews.
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Author NameGrokking the Low LevelDesign Interview Using OODPrinciples
Developed by MAANG Engineers
Every Educative lesson is designed by a team of ex-MAANG software engineers and PhD computer science educators, and developed in consultation with developers and data scientists working at Meta, Google, and more. Our mission is to get you hands-on with the necessary skills to stay ahead in a constantly changing industry. No video, no fluff. Just interactive, project-based learning with personalized feedback that adapts to your goals and experience.
ABOUT THIS COURSE
Low-level design interviews test something most engineers don't practice enough: taking a vague, open-ended prompt as "design a parking lot" or "design Stack Overflow" and turning it into a structured, implementable system with clearly defined classes, relationships, and behaviors. Knowing what inheritance is won't get you through. You need to demonstrate that you can use it to model a real system under time pressure. This course teaches that skill through repetition across 20+ real-world design problems. Each one follows the same structured approach: define requirements, identify key objects and relationships, model the system with UML diagrams (class, use case, sequence, activity), and then implement working code. By the time you've designed your fifth or sixth system, the process becomes second nature, which is exactly the point. We start with the foundations: OOP concepts, SOLID principles, and the most commonly tested design patterns. Then we move into the problems themselves: parking lots, elevator systems, Amazon's online shopping platform, chess, LinkedIn, and more. Each problem comes with a full walkthrough and a mock interview so you can test yourself under realistic conditions. Whether you're preparing for your first low-level design round or you've been avoiding this part of the loop, this course gives you a repeatable framework for breaking down any OOD problem systematically.

Trusted by 2.9 million developers working at companies

Been following this course for the last 15-20 days and during this period this course helped to me to get well versed in OOD principles and design

A

Amir Sayyed

Learner

The course was incredibly insightful. It provided a solid foundation in OOP principles, design patterns, and real-world system design problems. The structured approach and practical examples helped me grasp complex concepts effectively. Highly recommend Educative's course for anyone preparing for LLD interviews!

S

Sunil Kumawat

Senior Software Engineer @ Detech Technologies

Highly structured course with practical app examples and in-depth high-level architecture discussions

K

Krishna K.

Spotnana

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Frequently Asked Questions

What is an object-oriented design interview?

An object-oriented design (OOD) interview is a specialized technical interview used to evaluate your understanding of object-oriented programming principles and your ability to apply these principles to solve design problems. Typically lasting 45-60 minutes, this interview covers the basics of object-oriented programming and more complex concepts such as design principles and patterns. This is crucial for roles at major tech companies like Apple, Google, Meta, Microsoft, and Amazon.

How to prepare for an OOD interview?

When solving OOD interview questions, be sure to ask questions to clarify any aspects of the requirements you might not fully understand. It’s important not to rush into coding right away. Take a moment to identify the key objects involved in the solution and understand their relationships at a high level. Finally, describe the attributes and behaviors of each object to ensure a comprehensive design approach.

What are the principles of Low-Level Design?

Low-Level Design (LLD) revolves around a set of key principles that guide how software components are structured to work together efficiently. The main focus of LLD is all about breaking down a system into smaller, manageable parts so that developers can build systems that are flexible, easy to debug, and can adapt to changes more effectively.

How do you answer Low-Level Design questions?

To answer a Low-Level Design (LLD) problem, understand the problem’s requirements and avoid making unfounded assumptions. Next, draw class diagrams, and use case diagrams and schema diagrams to find the data model. Once you have the structure, go ahead and write the code using design patterns, OOD, and SOLID principles. Developers can take courses to practice mock Low-Level Design questions.

What is the primary focus of this course?

The course focuses on object-oriented design (OOD) fundamentals and provides real-world problems to help prepare for OOD interviews.

Who should take this course?

This course is suitable for software engineers preparing for OOD interviews at major tech companies such as Apple, Google, and Microsoft.

What skills will I gain from this course?

You’ll learn essential OOD concepts, design principles, patterns, and the ability to break down design problems using a bottom-up approach.

What tools will I use to present solutions?

You will use class, use case, sequence, and activity diagrams to present your design solutions.

How will this course help me in a software engineering interview?

The course provides real-world OOD problems similar to what you’ll encounter in interviews, helping you practice effective problem-solving and presentation skills.

What companies’ interview processes are referenced in this course?

The course focuses on the interview processes of major tech companies, such as Google, Meta, Amazon, Microsoft, and Apple.