Low-level System Design (LLD) Handbook | Coding Shuttle

Progress

0%

What is Software Design?High-Level vs Low-Level Design — Drawing the Boundary Software Architecture vs Software Design Functional vs Non-Functional Requirements The Software Design Process and Design Thinking Characteristics of Good Software Design Common Software Design Mistakes How to Read and Write Design Documents The Framework: How to Approach LLD Problems

Introduction to OOP and the Java Memory Model Classes, Objects, and the this Keyword Constructors and Object Initialization Encapsulation and Access Modifiers Abstraction : Interfaces vs Abstract Classes Inheritance and Its Types Polymorphism : Compile-Time vs Runtime Association, Aggregation, and Composition Dependency Relationships Generics and Type Safety The Golden Rule : Composition Over Inheritance

Introduction to Design Principles Single Responsibility Principle Open-Closed Principle Liskov Substitution Principle Interface Segregation Principle Dependency Inversion Principle DRY, KISS, and YAGNI Principles High Cohesion and Loose Coupling Law of Demeter Separation of Concerns and Information Hiding Designing for Testability : The Ultimate Proof of Loose Coupling

Why UML Matters in LLD Class Diagrams Sequence Diagrams Activity Diagrams State Diagrams Component and Object Diagrams Using UML Effectively in Interviews Common UML Mistakes to Avoid

What Are Design Patterns?History and the Gang of Four Categories of Design Patterns How to Choose a Design Pattern Anti-Patterns and Common Misuse Design Patterns Interview Strategy

Creational Patterns Overview Singleton Pattern: Including Thread-Safe and Bill Pugh Implementations Factory Method Pattern Abstract Factory Pattern Builder and Fluent Builder Pattern Prototype Pattern Factory vs Builder : When to Use Which Real-World Usage of Creational Patterns

Structural Patterns Overview Adapter Pattern Bridge Pattern Composite Pattern Decorator Pattern Facade Pattern Proxy Pattern Flyweight Pattern Adapter vs Facade vs Proxy Real-World Usage of Structural Design Patterns — How Spring Security Uses Filters and Proxies

Behavioral Patterns Overview Strategy Pattern Observer Pattern Command Pattern Chain of Responsibility Template Method Pattern State Pattern Mediator Pattern Iterator Pattern Memento Pattern Visitor Pattern Strategy vs State — Key Differences Real-World Usage of Behavioral Patterns

Introduction to Domain Modeling Identifying Entities and Value Objects Aggregates and Aggregate Roots Domain Services Repositories in Domain Design Business Rules Modeling Domain Events Designing Rich vs Anemic Domain Models Putting It Together — Full Domain Model Walkthrough

Introduction to API Design — Principles and Goals REST Principles and Resource Modeling DTO Design and Mapping Strategies — MapStruct and Jackson Request and Response Design Input Validation Design Error Handling and Standardized Error Responses Pagination, Filtering and Sorting API Versioning Strategies Idempotency in APIs API Security Basics Designing Internal vs External APIs

Introduction to Persistence Design The Repository Pattern — Spring Data JPA Under the Hood DAO vs Repository Pattern Transactions and ACID Properties Unit of Work Pattern Optimistic vs Pessimistic Locking Lazy Loading vs Eager Loading and the N+1 Problem Caching Fundamentals Write-Through vs Write-Back vs Cache-Aside Persistence Design Best Practices Designing for Data Consistency in Concurrent Systems

Introduction to Concurrency — Threads vs Processes Thread Lifecycle Thread Class vs Runnable vs Callable The Executor Framework and Thread Pools Synchronization and Locks ReentrantLock and ReadWriteLock Semaphores and Countdown Latches Concurrent Collections — ConcurrentHashMap and Friends Future and CompletableFuture for Async Design Thread Communication — Wait, Notify, NotifyAll Common Concurrency Problems — Deadlock, Starvation, Race Conditions Designing Thread-Safe Classes Concurrency Design Best Practices

Introduction to Event-Driven Architecture The Publisher-Subscriber Model Observer Pattern vs Pub-Sub — Where They Differ Event Modeling — Designing Good Events Message Queues — Concepts and Internal Design Eventual Consistency and What It Means for Object Design Event Sourcing — Concepts and When to Use It CQRS — Command Query Responsibility Segregation Common Pitfalls in Event-Driven Systems

Logging Fundamentals and Best Practices Audit Logging Monitoring and Metrics Design Health Checks Retry Mechanisms and Backoff Strategies Circuit Breaker Pattern Rate Limiting Algorithms Feature Flags Designing for Observability — Putting It All Together

How to Approach Any LLD Case Study — The 45-Minute Framework Design a Parking Lot Design an Elevator System Design a Vending Machine Design an ATM Machine Design a Chess Game Design Tic-Tac-Toe Design Snake and Ladder Design a Library Management System Design a Logging Framework Design an Inventory Management System Design a Car Rental System Design a Hotel Booking System Design a URL Shortener Design Splitwise

Advanced LLD — What Changes at the Senior Level Design a Movie Ticket Booking System — Handling Concurrency and Locking Design an E-Commerce Shopping Cart and Order Flow Design a Notification System — Internal Class Orchestration Design a Rate Limiter Design a Job Scheduler Design a Real-Time Chat System — WebSocket Handlers and Message Queues at the Class Level Design a Pub-Sub System Like Kafka — Internal Data Structures of the Broker Design a Payment Processing System Requirement Gathering Techniques for Interviews Identifying Entities and Relationships Under Pressure Choosing Design Patterns in an Interview Discussing Trade-Offs Confidently Common LLD Interview Mistakes Mock LLD Interview Walkthrough — End to End What to Do After the Interview — Learning from Every Session