As your application grows, a single backend often turns into a tangled mess — harder to scale, test, and deploy. That’s where microservice architecture comes in. Instead of one large codebase, you split your app into independent, loosely coupled services — each handling one specific business function (like users, products, or orders). In this blog, we’ll build a simple microservice-based system using: 🟢 Node.js + Express — for APIs 🍃 MongoDB — as individual service databases 🐳 Docker Compose — to run them together 🧠 What Are Microservices? Microservices are small, autonomous services that communicate over APIs. Each service: Has its own database Runs independently Can be scaled or deployed separately Example: A shopping app might have: 👤 User Service → handles signup/login 📦 Product Service → manages items 🛒 Order Service → processes purchases Instead of one app handling all three, you split them like this: [User Service] ...