Building Scalable APIs with Node.js

Introduction

Building scalable APIs is one of the most important skills for a backend developer. In this post, I’ll share my experience and best practices from building APIs that handle thousands of requests per second at Sohagame.

1. Project Structure

A well-organized project structure is the foundation of maintainable code:

src/
├── controllers/    # Request handlers
├── services/       # Business logic
├── models/         # Data models
├── middleware/      # Custom middleware
├── routes/         # Route definitions
├── utils/          # Helper functions
└── config/         # Configuration

2. Error Handling

Always implement a centralized error handler:

class AppError extends Error {
  constructor(message, statusCode) {
    super(message);
    this.statusCode = statusCode;
    this.isOperational = true;
  }
}

// Global error middleware
app.use((err, req, res, next) => {
  const statusCode = err.statusCode || 500;
  res.status(statusCode).json({
    status: 'error',
    message: err.isOperational ? err.message : 'Internal server error',
  });
});

3. Input Validation

Use libraries like Joi or Zod for request validation:

const createUserSchema = z.object({
  name: z.string().min(2).max(100),
  email: z.string().email(),
  role: z.enum(['admin', 'user']).default('user'),
});

4. Rate Limiting & Caching

For high-traffic APIs, always implement rate limiting and caching:

• Rate limiting: Use express-rate-limit to prevent abuse
• Caching: Redis for frequently accessed data
• Response compression: Use compression middleware

Conclusion

These patterns have helped me build APIs that scale to handle millions of requests. The key is starting with a solid foundation and iterating based on real-world metrics.