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Course Roadmap

Last Updated: January 12, 2026

This course covers lot of ground: object-oriented fundamentals, design principles, design patterns, and common LLD interview questions.

Use the filters below to tailor your prep by difficulty and experience level.

18 sections173 chapters
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Welcome
Course Introduction
Course Roadmap
Join the Community
LLD Introduction
What is LLD?Beginner
LLD vs HLDBeginner
Types of LLD interviewsBeginner
Quiz: Introduction
OOP Fundamentals
Classes and ObjectsBeginner
Exercise: Classes and Objects
EnumsBeginner
Exercise: Enums
InterfacesBeginner
Exercise: Interfaces
EncapsulationBeginner
Exercise: Encapsulation
AbstractionBeginner
Exercise: Abstraction
InheritanceBeginner
Exercise: Inheritance
PolymorphismBeginner
Exercise: Polymorphism
Quiz: OOP Fundamentals
Class Relationships
AssociationBeginner
Exercise: Association
AggregationBeginner
Exercise: Aggregation
CompositionBeginner
Exercise: Composition
DependencyIntermediate
Exercise: Dependency
RealizationIntermediate
Exercise: Realization
Quiz: Class Relationships
Design Principles
DRY PrincipleBeginner
Exercise: DRY Principle
KISS PrincipleBeginner
Exercise: KISS Principle
YAGNI PrincipleBeginner
Exercise: YAGNI Principle
Law of DemeterIntermediate
Exercise: Law of Demeter
Separation of ConcernsIntermediate
Exercise: Separation of Concerns
Coupling and CohesionIntermediate
Exercise: Coupling and Cohesion
Composing Objects PrincipleIntermediate
Exercise: Composing Objects Principle
Quiz: Design Principles
SOLID Principles
Single Responsibility PrincipleIntermediate
Exercise: Single Responsibility Principle
Open/Closed PrincipleIntermediate
Exercise: Open/Closed Principle
Liskov Substitution PrincipleIntermediate
Exercise: Liskov Substitution Principle
Interface Segregation PrincipleIntermediate
Exercise: Interface Segregation Principle
Dependency Inversion PrincipleIntermediate
Exercise: Dependency Inversion Principle
Quiz: SOLID Principles
UML
Class DiagramBeginner
Use Case DiagramBeginner
Sequence DiagramIntermediate
Activity DiagramIntermediate
State Machine Diagram
Quiz: UML
Design Patterns
Intro to Design PatternsBeginner
Creational
SingletonBeginner
Exercise: Singleton
BuilderBeginner
Exercise: Builder
Factory MethodBeginner
Exercise: Factory Method
Abstract FactoryIntermediate
Exercise: Abstract Factory
PrototypeIntermediate
Exercise: Prototype
Quiz: Creational Design Pattern
Structural
AdapterBeginner
Exercise: Adapter
FacadeBeginner
Exercise: Facade
DecoratorBeginner
Exercise: Decorator
CompositeIntermediate
Exercise: Composite
ProxyIntermediate
Exercise: Proxy
BridgeAdvanced
Exercise: Bridge
FlyweightAdvanced
Exercise: Flyweight
Quiz: Structural Design Pattern
Behavioral
StrategyBeginner
Exercise: Strategy
IteratorBeginner
Exercise: Iterator
ObserverIntermediate
Exercise: Observer
CommandIntermediate
Exercise: Command
StateIntermediate
Exercise: State
Template MethodIntermediate
Exercise: Template Method
Chain of ResponsibilityIntermediate
Exercise: Chain of Responsibility
VisitorAdvanced
Exercise: Visitor
MediatorAdvanced
Exercise: Mediator
MementoAdvanced
Exercise: Memento
Quiz: Behavioral Design Pattern
Additional Patterns
Null Object PatternIntermediate
Repository PatternIntermediate
MVC PatternIntermediate
Dependency Injection PatternIntermediate
Specification PatternAdvanced
Game Loop PatternAdvanced
Thread Pool PatternAdvanced
Producer Consumer PatternAdvanced
Quiz: Additional Patterns
LLD Interview Tips
How to approach OOD InterviewsBeginner
How to approach Maching Coding InterviewsBeginner
How to Identify Entities and Model RelationshipsIntermediate
How to write Clean CodeBeginner
How to choose Design PatternsIntermediate
How to handle Concurrency ScenariosIntermediate
Games & Puzzles
Design Tic Tac ToeBeginner
Design Snake and Ladder GameBeginner
Design Minesweeper GameIntermediate
Design Chess GameAdvanced
Data Structures & Search
Design LRU CacheBeginner
Design Bloom FilterBeginner
Design Search Autocomplete SystemBeginner
Design Simple Search EngineIntermediate
Managing States
Design ATMIntermediate
Design Vending MachineIntermediate
Design Elevator SystemIntermediate
Design Traffic Control SystemIntermediate
Design Coffee Vending MachineAdvanced
Management Systems
Design Parking LotBeginner
Design Task Management SystemBeginner
Design Inventory Management SystemIntermediate
Design Library Management SystemIntermediate
Design Restaurant Management SystemAdvanced
Social & Content Platforms
Design Stack OverflowIntermediate
Design a Social NetworkIntermediate
Design Learning PlatformIntermediate
Design CricinfoAdvanced
Design LinkedInAdvanced
Design SpotifyAdvanced
Communication & Messaging
Design Notification SystemBeginner
Design Pub Sub SystemIntermediate
Design Chat ApplicationIntermediate
Financial & Payment Systems
Design SplitwiseIntermediate
Design Payment GatewayIntermediate
Design Online Stock ExchangeAdvanced
E-commerce & Booking Systems
Design Amazon LockerIntermediate
Design Shopping CartIntermediate
Design AmazonAdvanced
Design Movie Booking SystemAdvanced
Design Car Rental SystemAdvanced
Design Meeting SchedulerAdvanced
Design Online Auction SystemAdvanced
Design Online Food Delivery ServiceAdvanced
Design Ride Hailing ServiceAdvanced
Developer Tools & Infrastructure
Design URL ShortenerIntermediate
Design Logging FrameworkIntermediate
Design Rate LimiterIntermediate
Design In Memory File SystemAdvanced
Design Version Control SystemAdvanced
Design Task SchedulerAdvanced