A standard structure for building organized and scalable Node.js backends, especially with Express and MongoDB (via Mongoose).

✨ It's just an overview — we’ll learn this throughout the notes!

📦 Root Structure

project-root/
│
├── 📁 src/                ← All source code lives here
│   ├── 📁 config/         ← Configuration files (DB, environment)
│   ├── 📁 controllers/    ← Route handlers (business logic)
│   ├── 📁 routes/         ← Express route definitions
│   ├── 📁 models/         ← Mongoose schemas or DB models
│   ├── 📁 middlewares/    ← Custom middleware (auth, logger, error handler)
│   ├── 📁 services/       ← Business logic (email, upload, etc.)
│   ├── 📁 utils/          ← Helper functions (e.g., formatters, generators)
│   ├── 📁 validations/    ← Joi/Yup request schema validators
│   ├── 📁 constants/      ← Static config (roles, status codes)
│   └── app.js            ← Express app config
│
├── 📄 .env                ← Environment variables
├── 📄 .gitignore          ← Ignore node_modules, .env, etc.
├── 📄 package.json        ← Project metadata & dependencies
├── 📄 server.js           ← App entry point (starts the server)
└── 📄 README.md           ← Project documentation

🧠 Folder Descriptions

Folder / File Purpose
src/config MongoDB config, app settings, 3rd-party API keys
src/controllers Logic for handling requests/responses
src/routes URL paths and associated controllers
src/models Mongoose schemas or database models
src/middlewares Auth, error handling, validation logic
src/services Reusable business logic like sending emails or hashing passwords
src/utils Pure utility functions (formatters, generators)
src/validations Input validation rules using Joi, Yup, or custom logic
src/constants Reusable static values like user roles, error messages
src/app.js Main Express app setup file
server.js Loads and runs app.js, listens on a port

⚙️ Example server.js


const app = require('./src/app');
const PORT = process.env.PORT || 3000;

app.listen(PORT, () => {
  console.log(`🚀 Server running on port ${PORT}`);
});

⚙️ Example app.js


const express = require('express');
const dotenv = require('dotenv');
const noteRoutes = require('./routes/noteRoutes');
const connectDB = require('./config/db');

dotenv.config();
connectDB();

const app = express();
app.use(express.json());

app.use('/api/notes', noteRoutes);

module.exports = app;

✅ Best Practices