Skip to content
Guide Docs

Express.js Best Practices & Performance

Building an Express application is easy, but making it production-ready requires attention to performance, reliability, and security. In this guide, we’ll explore best practices to ensure your application can handle high traffic and remain stable.

1. Use Compression

Gzip compression can significantly reduce the size of the response body, increasing the speed of your web app. Express has the compression middleware for this.

Installation

Terminal window
npm install compression

Usage

const compression = require('compression');
const express = require('express');
const app = express();


app.use(compression());

2. Avoid Synchronous Functions

Node.js is single-threaded. If you use synchronous functions (like fs.readFileSync), you block the entire event loop, preventing the server from handling other requests.

Bad (Blocking):

const data = fs.readFileSync('large-file.json'); // Blocks the event loop

Good (Non-blocking):

fs.readFile('large-file.json', (err, data) => {
  // Handles result asynchronously
});

3. Use a Production Process Manager

In development, you might run your app with node app.js. In production, you should use a process manager like PM2. PM2 ensures your app restarts automatically if it crashes and allows you to run multiple instances (clustering).

Installation

Terminal window
npm install pm2 -g

Basic Commands

Terminal window
pm2 start app.js -i max  # Start app in cluster mode using all CPUs
pm2 status               # Check status of apps
pm2 logs                 # View real-time logs

4. Proper Logging

Don’t use console.log in production. It’s synchronous and lacks features like log levels and rotation. Instead, use a logging library like Winston or Morgan.

  • Morgan: For HTTP request logging.
  • Winston: For general application logging (errors, info).
const morgan = require('morgan');
app.use(morgan('combined')); // Standard Apache combined log output

5. Set NODE_ENV to production

Always ensure your environment variable NODE_ENV is set to production. Express and many other libraries use this flag to enable optimizations (like caching views and omitting error stacks).

Terminal window
export NODE_ENV=production
node app.js

6. Handle Exceptions Properly

Uncaught exceptions can crash your server. Use try-catch in async functions and define a global error handler.

app.get('/data', async (req, res, next) => {
  try {
    const result = await someAsyncAction();
    res.json(result);
  } catch (err) {
    next(err); // Pass to global error handler
  }
});

Key Takeaways

  • Compression reduces payload size.
  • Asynchronous code keeps the event loop free.
  • PM2 provides reliability and scaling.
  • Structured logging helps with debugging in production.
  • NODE_ENV=production is a mandatory setting for performance.

Applying these best practices will make your Express.js applications faster, more scalable, and more reliable!