Building Scalable APIs with Node.js and Express

## Introduction

Building APIs that can scale is one of the most important skills for modern backend developers. In this guide, we'll explore the best practices for creating production-ready APIs.

Project Setup

First, let's set up our project with the necessary dependencies:

npm init -y
npm install express cors helmet morgan compression
npm install -D typescript @types/node @types/express

Rate Limiting

One of the first things you should implement is rate limiting to protect your API from abuse:

const limiter = rateLimit({ windowMs: 15 * 60 * 1000, // 15 minutes max: 100, // limit each IP to 100 requests per windowMs message: 'Too many requests, please try again later.', });

app.use('/api/', limiter); ```

Caching Strategies

Implementing proper caching can dramatically improve your API's performance:

const redis = new Redis(process.env.REDIS_URL);

async function getCachedData(key: string) { const cached = await redis.get(key); if (cached) return JSON.parse(cached); return null; }

async function setCachedData(key: string, data: any, ttl = 3600) { await redis.set(key, JSON.stringify(data), 'EX', ttl); } ```

Database Optimization

Connection Pooling

Always use connection pooling for your database connections:

const pool = new Pool({ connectionString: process.env.DATABASE_URL, max: 20, idleTimeoutMillis: 30000, connectionTimeoutMillis: 2000, }); ```

Query Optimization

• ▹Use indexes on frequently queried columns
• ▹Avoid N+1 queries by using JOINs or batch loading
• ▹Use EXPLAIN ANALYZE to understand query performance

Conclusion

Building scalable APIs requires attention to detail in many areas. By implementing proper rate limiting, caching, and database optimization, you can build APIs that handle millions of requests efficiently.