Express.js

Express.js, or simply Express, is a back end web application framework for building RESTful APIs with Node.js, released as free and open-source software under the MIT License. It is designed for building web applications and APIs.^[2] It has been called the de facto standard server framework for Node.js.^[3]

Express.js

Original author(s)	TJ Holowaychuk
Developer(s)	OpenJS Foundation and others
Initial release	16 November 2010; 14 years ago (2010-11-16)
Stable release	5.1.0 / March 31, 2025; 28 days ago[1]
Repository	github.com/expressjs/express
Written in	JavaScript
Platform	Node.js
Type	Web framework
License	MIT License
Website	expressjs.com

The original author, TJ Holowaychuk, described it as a Sinatra-inspired server,^[4] meaning that it is relatively minimal with many features available as plugins. Express is the back-end component of popular development stacks like the MEAN, MERN or MEVN stack, together with the MongoDB database software and a JavaScript front-end framework or library.^[5]

History

Express.js was founded by TJ Holowaychuk. The first release, according to Express.js's GitHub repository, was on 22 May 2010. Version 0.12

In June 2014, rights to manage the project were acquired by StrongLoop.^[6] StrongLoop was acquired by IBM in September 2015;^[7] in January 2016, IBM announced that it would place Express.js under the stewardship of the Node.js Foundation incubator.^[8]

Features

• Robust routing
• Concentrate on high-performance
• HTTP helpers (redirection, caching, etc..).
• Asynchronous programming

Popularity

Express.js is used by Fox Sports, PayPal, Uber and IBM.^[9]

Example

The following program will respond to HTTP GET requests with the text 'Hi, your request has been received', and listen to the port the program is running on (in this case, port 2000).

// Importing the Express library.
const express = require('express');

// Initializing the app.
const app = express();

// Getting the path request and sending the response with text.
app.get('/', (req, res) => {
    res.send('Hi, your request has been received');
});

// Listening on port 2000.
app.listen(2000, () => {
    console.log('listening at http://localhost:2000');
});

See also

• JavaScript framework
• Meteor
• Socket.IO