A structured NestJS learning repository — covering architecture, dependency injection, modules, controllers, pipes, validation, exception filters, database integration, and environment config. Each folder has working code and detailed notes.

NestJS brings opinionated structure to Node.js backends — this repo works through that structure systematically, from how a NestJS app boots up to building a full REST API with validation, error handling, and a database layer.

• Who This Is For
• Modules
• How to Use
• Prerequisites
• About

• Node.js/Express developers moving to NestJS who want to understand its architecture properly
• Backend developers building enterprise-grade APIs and needing a reference for NestJS patterns
• Developers who learn by reading structured notes alongside working code

Each folder contains:

• TypeScript source files — working NestJS code
• Notes/Guide files — theory, patterns, and explanations

Three architecture diagrams are included at the repo root:

• What is Nest.js?.png — NestJS overview and positioning vs Express
• How nestJs App start.png — bootstrap flow from main.ts to first request
• Nest.js syllabus.png — full topic map

# 1. Clone the repo
git clone https://github.com/Wcoder547/NestJS.git
cd NestJS

# 2. Navigate to any module
cd "REST API"

# 3. Install dependencies
npm install

# 4. Start the dev server
npm run start:dev

API runs at http://localhost:3000 by default.

basics → Architecture → routingAndController → services → modules
  → dependency-injection → pipes → validation → exception-filter
  → Config-Module&env → Guide-db → REST API

Start with basics and Architecture together — understanding how NestJS boots and how its layers relate makes everything else predictable.

• Node.js v18+
• TypeScript basics (decorators, classes, interfaces)
• Some prior Express.js or Node.js experience helps but isn't required

NestJS is what happens when you take Node.js seriously as an enterprise backend platform — it enforces separation of concerns, makes dependency injection a first-class citizen, and gives teams a shared language for structuring applications.

This repo was built to understand that structure from the inside out: not just how to use @Controller and @Injectable, but why the architecture is shaped the way it is, what problem each layer solves, and how all the pieces connect when you build a real API.

Built by Waseem Akram — Full-Stack Developer and DevOps Engineer based in Pakistan, working across the MERN stack, Generative AI integrations, and cloud automation.

If this helped you, consider giving it a ⭐