Building Scalable APIs with Node.js and Express

Creating APIs that can handle growth and scale with your application is crucial for long-term success. In this guide, we'll explore best practices for building robust APIs with Node.js and Express.

Project Architecture

Start with a well-organized structure:

src/
├── controllers/
├── middleware/
├── models/
├── routes/
├── services/
├── utils/
└── app.js

Express Setup

const express = require('express');
const helmet = require('helmet');
const cors = require('cors');
const compression = require('compression');

const app = express();

// Security middleware
app.use(helmet());
app.use(cors());

// Performance middleware
app.use(compression());
app.use(express.json(\{ limit: '10mb' \}));

Error Handling

Implement comprehensive error handling:

const errorHandler = (err, req, res, next) => \{
  let error = { ...err \};
  error.message = err.message;

  // Log error
  console.error(err);

  // Mongoose bad ObjectId
  if (err.name === 'CastError') \{
    const message = 'Resource not found';
    error = { message, statusCode: 404 \};
  }

  res.status(error.statusCode || 500).json(\{
    success: false,
    error: error.message || 'Server Error'
  \});
};

Database Integration

Use proper connection pooling and error handling:

const mongoose = require('mongoose');

const connectDB = async () => \{
  try {
    const conn = await mongoose.connect(process.env.MONGO_URI, {
      maxPoolSize: 10,
      serverSelectionTimeoutMS: 5000,
      socketTimeoutMS: 45000,
    \});
    
    console.log(`MongoDB Connected: $\{conn.connection.host\}`);
  } catch (error) \{
    console.error('Database connection failed:', error);
    process.exit(1);
  \}
};

Performance Optimization

1. Caching: Implement Redis for frequently accessed data
2. Rate Limiting: Protect against abuse
3. Compression: Reduce response sizes
4. Database Indexing: Optimize query performance

Security Best Practices

• Use HTTPS in production
• Implement proper authentication
• Sanitize user inputs
• Set appropriate CORS policies
• Use environment variables for secrets

Following these patterns will help you build APIs that can grow with your application.