Fastify Done Right: Modules, Dependencies, and Real Structure

In this video, we refactor a basic Node.js + Fastify backend into a modular monolith that’s clean, testable, and ready to evolve into microservices later.

We start from a typical “everything in index.js” setup with controllers, routes, repositories, and services mixed together. Step by step, we introduce a proper modules folder and split the app into User, Catalog, and Shopping modules, plus a Shared module for cross-cutting concerns.