Express and TypeScript - Build Your Own API framework from Scratch | Full Masterclass | 3+ hours

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Build Your Own Express + TypeScript Framework (Full Course | 3+ Hour Masterclass) Pre-Requisite playlist before taking this course https://www.youtube.com/playlist?list=PLyxTh1BOCzsGSw2vFbkWipQTnnyjZPZxm This course is also available as Individual chapters in the playlist below https://www.youtube.com/playlist?list=PLyxTh1BOCzsHaR5vaHbiWbv_FGseSptIT The full course download available with the below link Coming soon……….. NPM commands used to install all the dependencies npm install class-transformer class-validator dotenv express pg reflect-metadata typedi npm install typeorm typeorm-typedi-extensions npm install -D @types/express @types/node nodemon typescript ts-node 🧠 Don’t just use frameworks. Learn how to build them. From Scratch to Scalable Backend Architecture This is a complete 3+ hour masterclass where we build a custom backend framework using Express and TypeScript from scratch — step by step. If you’ve ever used frameworks and wondered “how does this actually work under the hood?” — this video is for you. We don’t just build an app. We design a framework-level architecture with decorators, dependency injection, middleware system, DTOs, database integration, and more. What you’ll learn in this masterclass 🧱 Foundation & Architecture • Setting up a scalable Express + TypeScript project • Structuring applications like real-world frameworks • Understanding Dependency Injection (DI) and its challenges • Why DI frameworks exist and how they solve real problems 🎯 Decorators & Routing System • Building custom @Controller and @Get decorators • Using TypeScript decorators & reflection metadata • Dynamically mapping controllers to Express routes • Creating a framework-like routing layer ⚡ Dynamic Module Loading • Auto-loading controllers at runtime • Eliminating manual wiring • Building a clean application bootstrap system • Convention over configuration approach 🔗 Middleware System (Framework Style) • Controller-level vs method-level middleware • Creating @UseMiddleware decorator • Attaching middleware using reflection • Designing reusable middleware classes 🎯 Request Handling with Decorators • Building @Param() and @Query() decorators • Extracting request data cleanly • Dynamic argument resolution • Cleaner and more readable controllers 📦 Request Body & DTOs • Creating @Body() decorator • Introduction to DTO (Data Transfer Object) • Type-safe request handling • Designing clean API contracts 🏗️ Service Layer & Config Management • Designing a proper Service Layer • Moving business logic out of controllers • Building a Config Service • Managing environment variables cleanly 🗄️ Database Integration (TypeORM + PostgreSQL) • Setting up TypeORM with PostgreSQL • Creating Entities • Generating and running migrations • Reverting migrations safely • Implementing full CRUD operations • Connecting service layer with repositories 🧠 What makes this different? • No magic — everything is built from scratch • Deep dive into how frameworks actually work • Focus on clean architecture & scalability • Inspired by real-world frameworks like NestJS 🧱 Who is this for? • Backend developers (Node.js / Express) • Developers learning TypeScript deeply • Engineers preparing for system design & interviews • Anyone who wants to go beyond tutorials and build real architecture ⏱️ Chapters 00:00 Project Introduction 05:09 Project Setup 10:45 App and controller Setup 33:11 Route Decorator Setup 58:52 Loading Controllers Dynamically 01:10:14 Middleware Setup 01:38:06 Central Response and Error Handling 01:54:19 Param and Query Decorator 02:15:43 Body Decorator and DTO 02:34:55 Service Layer and Config Service 02:52:32 Postgres and TypeORM setup 03:30:44 Final Code Refactoring 📌 Why you should watch this By the end of this video, you’ll: • Understand how backend frameworks are designed • Be able to build your own mini-framework • Write cleaner, scalable, production-ready code 👉 Subscribe for more deep-dive backend content 👉 Like & share if this helped you understand frameworks #expressjs #TypeScript #DependencyInjection #BackendDevelopment #NodeJS #FrameworkDesign #CleanArchitecture #SoftwareEngineering My Blog Page: https://codewithsoumyajeet.com/ Subscribe to my newsletter: https://codewithsoumyajeet.com/newsletter/ Linked In: https://www.linkedin.com/in/soumyajeet-nayak-82593a79/ Instagram: https://www.instagram.com/code_with_soumyajeet/ Subscribe to YouTube Channel : https://www.youtube.com/channel/UCkoVDxXrQVuRjMIM3SnqXEQ Please like the video and Subscribe to my Channel