Logging in Express with Morgan and Winston

When building a Node.js/Express app, logging is essential for debugging, monitoring, and keeping track of application behavior — both during development and in production.

In this post, we'll explore two powerful logging tools for Express:

• Morgan – A lightweight HTTP request logger
• Winston – A robust, customizable logger for application-level events

Why Logging Matters

Logging helps you:

• Track user requests and responses
• Debug server-side errors
• Monitor performance and behavior in production
• Audit events or suspicious activity

Morgan: HTTP Request Logger

📌 What is Morgan?

Morgan logs incoming HTTP requests in a predefined format. It's ideal for development and debugging routes.

Step 1: Install Morgan

npm install morgan

Step 2: Use Morgan in Your App

import express from 'express';
import morgan from 'morgan';

const app = express();

// Use 'dev' preset for concise logging
app.use(morgan('dev'));

app.get('/', (req, res) => {
  res.send('Hello World');
});

app.listen(3000, () => console.log('Server running'));

Output Example:

GET / 200 8.104 ms - 11

You can also use other formats like 'combined', 'short', or define your own:

app.use(morgan(':method :url :status :response-time ms'));

Winston: Flexible Application Logger

📌 What is Winston?

Winston is a general-purpose logging library. It allows you to:

• Log messages to console, files, or external services
• Set log levels (info, warn, error, etc.)
• Format logs (JSON, timestamps, custom formats)

Step 1: Install Winston

npm install winston

Step 2: Create a Logger Configuration

Create a logger.js file:

import winston from 'winston';

const logger = winston.createLogger({
  level: 'info', // minimum level to log
  format: winston.format.combine(
    winston.format.timestamp(),
    winston.format.printf(
      ({ timestamp, level, message }) =>
        `[${timestamp}] ${level.toUpperCase()}: ${message}`
    )
  ),
  transports: [
    new winston.transports.Console(), // log to console
    new winston.transports.File({ filename: 'logs/error.log', level: 'error' }),
    new winston.transports.File({ filename: 'logs/combined.log' })
  ]
});

export default logger;

Step 3: Use Winston in Your Routes

import logger from './logger.js';

app.get('/health', (req, res) => {
  logger.info('Health check route hit');
  res.send('OK');
});

app.get('/error', (req, res) => {
  logger.error('Something went wrong');
  res.status(500).send('Error');
});

Combining Morgan with Winston

You can use Morgan to log HTTP requests and pipe those logs into Winston for consistent formatting and file storage.

import morgan from 'morgan';
import logger from './logger.js';

const stream = {
  write: (message) => logger.info(message.trim())
};

app.use(morgan('combined', { stream }));

Summary

Final Thoughts

• Use Morgan during development to trace HTTP traffic.
• Use Winston in production for advanced logging, error tracking, and audit logs.
• Combine both for full-stack visibility.