AlgoInsight

Object Oriented Programming

Low Level Design Fundamentals

39-module low-level design course built for engineers - from LLD fundamentals and SOLID through UML, the GoF pattern catalogue, architectural patterns, and the design-quality muscle senior engineers use in interviews.

Beginner1730188 lessons13 free lessonslldlow-level-designoopdesign-patternssolid

Low Level Design Fundamentals

This isn't a pattern-of-the-week tour. It's a 39-module Low-Level Design curriculum built around how senior engineers actually think about object-oriented design — language fundamentals plus the depth most interview-prep platforms never reach: SOLID at the level you can apply, UML as a design tool (not a documentation chore), the full GoF pattern catalogue with explicit selection heuristics, the architectural patterns interviewers expect at L4–L6 (Repository, Service Layer, Unit of Work, CQRS, Event Sourcing), and the design-quality dimensions (cohesion, coupling, code smells, refactoring, testability) that separate "works" from "well-designed."

You'll work through the fundamentals (classes, inheritance, abstraction, composition, class relationships), the principle stack (DRY/KISS/YAGNI, then all five SOLID principles as full modules with worked refactors), UML for design conversations, the design pattern catalogue (creational, structural, behavioral, additional patterns including DI/MVC/Game Loop, architectural — with explicit selection and combination guidance), the design-quality cluster (readability, cohesion, code smells, refactoring, testing-as-design-feedback), and the systems-design dimensions that senior interviews probe (concurrency, error handling, persistence, validation, observability, resilience, security, performance) — closing with type-driven design, designing for testability, API evolution, and the trade-off frameworks engineers carry into every design decision.

What you will learn

Course outline

Module 1: LLD Introduction

LLD Introduction — 3 topics.

Module 2: Classes And Objects

Classes And Objects — 7 topics.

Module 3: Inheritance And Polymorphism

Inheritance And Polymorphism — 6 topics.

Module 4: Abstractions And Interfaces

Abstractions And Interfaces — 5 topics.

Module 5: Composition Vs Inheritance

Composition Vs Inheritance — 4 topics.

Module 6: Class Relationships

Class Relationships — 4 topics.

Module 7: Design Principles

Design Principles — 6 topics.

Module 8: Single Responsibility Principle

Single Responsibility Principle — 5 topics.

Module 9: Open Closed Principle

Open Closed Principle — 4 topics.

Module 10: Liskov Substitution Principle

Liskov Substitution Principle — 4 topics.

Module 11: Interface Segregation Principle

Interface Segregation Principle — 4 topics.

Module 12: Dependency Inversion Principle

Dependency Inversion Principle — 4 topics.

Module 13: UML Diagrams

UML Diagrams — 6 topics.

Module 14: Creational Patterns

Creational Patterns — 6 topics.

Module 15: Structural Patterns

Structural Patterns — 8 topics.

Module 16: Behavioral Patterns Foundations

Behavioral Patterns Foundations — 4 topics.

Module 17: Behavioral Patterns State And Communication

Behavioral Patterns State And Communication — 4 topics.

Module 18: Behavioral Patterns Iteration And Composition

Behavioral Patterns Iteration And Composition — 4 topics.

Module 19: Additional Patterns

Additional Patterns — 6 topics.

Module 20: Architectural Patterns

Architectural Patterns — 8 topics.

Module 21: Pattern Selection And Combination

Pattern Selection And Combination — 4 topics.

Module 22: Readability

Readability — 4 topics.

Module 23: Cohesion And Coupling

Cohesion And Coupling — 4 topics.

Module 24: Code Smells

Code Smells — 4 topics.

Module 25: Refactoring

Refactoring — 4 topics.

Module 26: Testing As Design Feedback

Testing As Design Feedback — 4 topics.

Module 27: Design Quality Synthesis

Design Quality Synthesis — 4 topics.

Module 28: Concurrency

Concurrency — 4 topics.

Module 29: Error Handling

Error Handling — 4 topics.

Module 30: Persistence Patterns

Persistence Patterns — 8 topics.

Module 31: Validation

Validation — 4 topics.

Module 32: Observability

Observability — 4 topics.

Module 33: Resilience Patterns

Resilience Patterns — 8 topics.

Module 34: Security

Security — 4 topics.

Module 35: Performance

Performance — 4 topics.

Module 36: Type Driven Design

Type Driven Design — 6 topics.

Module 37: Designing For Testability

Designing For Testability — 4 topics.

Module 38: API Design And Evolution

API Design And Evolution — 4 topics.

Module 39: Trade Off Frameworks

Trade Off Frameworks — 4 topics.

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