Back to Premium Vault
Premium Course Syllabus

LLD (Low Level Design)

Condensed Placement Preparation Syllabus

OOP Design · SOLID · Design Patterns · Class Diagrams · Interview Ready

6 Modules
32 Topics
6 Quizzes
Design

Ideal For

SDE interviews at product-based companies — Amazon, Flipkart, Paytm, Swiggy
Machine Coding rounds (45–90 min design + code exercises)
Backend/full-stack developer interviews requiring OOP design skills
Students who want structured LLD preparation with real case studies

Module-Wise Curriculum

A concise, placement-focused syllabus — covers every key concept without overloading.

1

Module 1

Oop Refresher For Design

  • Classes, Objects & Relationships — association, aggregation, composition, dependency
  • Encapsulation & Abstraction — data hiding, minimal public interface principle
  • Inheritance vs Composition — when to prefer composition over inheritance
  • Polymorphism in Design — interface-based programming, duck typing, virtual dispatch
  • UML Class Diagrams — notation, arrows (inheritance, composition, association), multiplicity
Quiz — OOP Fundamentals for LLD
2

Module 2

Solid Principles

  • Single Responsibility Principle (SRP) — one class, one reason to change — examples
  • Open/Closed Principle (OCP) — open for extension, closed for modification — strategy pattern
  • Liskov Substitution Principle (LSP) — subclasses must be substitutable — rectangle vs square
  • Interface Segregation Principle (ISP) — fat interfaces vs lean interfaces, role interfaces
  • Dependency Inversion Principle (DIP) — depend on abstractions, not concretions — DI container
Quiz — SOLID Principles
3

Module 3

Creational & Structural Design Patterns

  • Singleton Pattern — thread-safe implementation (double-checked locking, enum singleton)
  • Factory Method & Abstract Factory — object creation without specifying exact class
  • Builder Pattern — constructing complex objects step by step, fluent API design
  • Adapter Pattern — wrapper around incompatible interfaces, legacy system integration
  • Decorator Pattern — adding behaviour dynamically, Java I/O streams example
  • Facade Pattern — simplified interface to a complex subsystem
Quiz — Creational & Structural Patterns
4

Module 4

Behavioural Design Patterns

  • Observer Pattern — event-driven programming, publish-subscribe model
  • Strategy Pattern — selecting algorithm at runtime, payment method example
  • Command Pattern — encapsulating requests as objects, undo/redo functionality
  • State Pattern — object behaviour changes with internal state, vending machine example
  • Iterator Pattern — sequential access without exposing internal structure
Quiz — Behavioural Patterns
5

Module 5

Machine Coding Case Studies

  • Parking Lot Design — floors, spots, vehicle types, ticket generation, payment
  • Library Management System — books, members, borrow/return, fine calculation
  • Elevator/Lift System — multiple lifts, floor requests, scheduling algorithm
  • Snake and Ladder Game — board, players, dice, snakes, ladders OOP model
  • ATM Machine Design — card, account, transaction, session, error handling
  • Cab Booking System (Uber) — driver, rider, trip, surge pricing overview
Quiz — Machine Coding Practice
6

Module 6

Interview Strategy & Code Quality

  • How to Approach a Machine Coding Problem — clarify → design → code → test
  • Writing Clean Code — meaningful names, small functions, no magic numbers
  • Extensibility Checklist — can you add a new feature without breaking existing code?
  • Top 10 LLD Interview Questions — with structured walk-through answers
  • Code Review Checklist — SOLID violations, pattern misuse, coupling issues
Quiz — LLD Interview Readiness

Pattern-First

Learn recurring patterns, not one-off tricks — the fastest path to solving new problems.

Placement-Ready

Every module ends with an assessment or drill mapped to the way rounds are actually run.

AI-Assisted

Unlimited AI Tutor, Mock Interviews and Resume Review are included with your subscription.

Unlock LLD (Low Level Design) and 13 more courses

One subscription. Every structured course, every AI tool, every private update — for a full year.

Low-Level Design (LLD) Notes & Interview Questions

Low-level design is where object-oriented thinking is tested in code. This course moves from SOLID principles and UML to the design patterns that appear in interviews — strategy, factory, observer, decorator, singleton, builder — and then into full machine-coding problems: parking lot, splitwise, elevator, BookMyShow, rate limiter, logging library.

Each problem is worked the way an interviewer expects: clarify requirements, identify entities, define responsibilities and interfaces, choose patterns with a reason, then handle concurrency and extension. You also get the vocabulary to justify a design instead of just producing classes.

What you'll learn in LLD (Low Level Design)

  • Oop Refresher For Design
  • Solid Principles
  • Creational & Structural Design Patterns
  • Behavioural Design Patterns
  • Machine Coding Case Studies
  • Interview Strategy & Code Quality

Why LLD (Low Level Design) matters for placements

Product companies use a machine-coding or LLD round to filter candidates who can only solve puzzles. Design rounds reward structure and communication, so they are learnable quickly — and they carry disproportionate weight for SDE-1 offers and internship conversions.

Free vs Premium — what's included

Free

  • This full module-wise syllabus and topic list
  • The free revision course for this subject
  • Free core CS question bank and roadmaps
  • Aptitude and DSA practice sheets

Premium

  • Full lesson content for every module listed above
  • Module quizzes and interview question sets
  • Worked examples, numericals and revision drills
  • All 14 premium placement courses, lifetime access

Frequently asked questions

What is the difference between LLD and HLD?

LLD is class-level design — entities, responsibilities, interfaces and patterns within one service. HLD is system-level — services, databases, caching, queues and scaling decisions.

How many design patterns should a fresher know?

Six to eight used well is enough: strategy, factory, observer, decorator, singleton, builder, adapter and template method. Knowing when not to use a pattern matters as much as naming it.

Are LLD rounds asked to freshers?

Yes, commonly as a 60–90 minute machine-coding round at product companies and startups, and as OOP design discussion in service-company technical rounds.

Also revise

High-Level Design (HLD)OOP CourseFree OOP Essentials