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What is Express.js? A Comprehensive Guide to Beginners

Lavesh Katariya
Lavesh Katariya
September 14, 2023
Clock icon9 mins read
Calendar iconLast updated September 14, 2023
Banner-What is Express js

Let’s start with web development.

When we talk about web development, we are basically essentially talking about the front-end and back-end (also referred to as server-side). Express is a backend development Nodejs framework.

What is a Nodejs Framework?

This section is for those who are not familiar with frameworks. If you already know what a framework is, please feel free to skip ahead.

Writing an application from scratch is time-consuming and tedious, especially in today's fast-paced world, and initial setup may involve a lot of boilerplate code, such as setting up ports and defining route handlers; frameworks help to save time and effort by providing a pre-built set of tools and libraries that can be used to quickly and easily create a web application. This can free up developers to focus on the things that matter most – writing logic and advanced functionalities.

What is Express js?

It is one of the most popular Node.js web application frameworks, used with popular tech stacks, like MERN, MEAN, and MEVN, for web development.  You've probably heard of these stacks if you're familiar with web development. And if you're new to web development, you'll need to learn about them.

Img-Expressjs tech stack

The image shows how a tech stack contributes to complete web development. For instance, when it comes to data storage, a Database (e.g., MongoDB) is required, and for writing the front end, various frameworks exist today, such as Angular.js.(in MEAN stack). 

Similarly, you need to use a backend-specific language or framework for the backend. Some popular backend languages include Python, Java, JavaScript (Node.js), and PHP, while Django, Express.js, and Flask are some of the popular backend frameworks.

If you want to use JavaScript in the backend, you typically need to use the Node.js runtime environment. Node.js allows you to run JavaScript code outside of a web browser, which makes it possible to use JavaScript for both the front end and back end of a web application.

On top of Nodejs, several frameworks have been created, among which is Express.  More precisely, it is a layer built around Node.js that significantly simplifies the process of working within the Node.js environment and reduces development complexity.

Express is an open-source web application framework for Node.js. It provides a robust set of features for building web and mobile applications, including routing, middleware, template engines, seamless database integration, and a wealth of features for developing advanced features and functions.

Note: In this article, when we refer to web applications with Express, we are explicitly referring to the development of “back-end services or APIs.”

Features of Express

An array of pre-built tools

The framework includes an array of tools for web applications, routing, and middleware for building and deploying large-scale, enterprise-ready applications.

Node package manager

It comes up with a Node package manager and a command-line interface(CLI), allowing you to create project structures, generate routes, controllers, and other components, as well as manage dependencies and configuration settings.


Middleware in Express is used as snippets of code that intercept requests and responses, manage errors, and perform various other tasks, helping you to perform actions like validation, logging, and authentication in a reusable and modular way.


ExpressJS offers developers a straightforward routing system that simplifies the handling of HTTP requests. In addition, it allows you to define your own special paths and rules for these requests.

Applications of Expressjs

It is termed as a versatile framework that developers employ for constructing APIs, single page and real-time applications, microservices, proxy servers, CMSs, backend for mobile applications, authentication, authorization mechanisms, and many more services. Below is a list of the application you can build using Express js.

1. APIs for Single Page Application

Single-page applications (SPAs) are a popular type of web application that loads all of the content for the page in one go. This means that the user does not have to wait for the page to reload when they interact with it, which can provide a smoother and more responsive experience.

Some popular examples of SPAs include Gmail, Google Maps, and Spotify. These apps are able to provide a great user experience because they only need to load the content once, and then they can dynamically update the content based on the user's actions. This makes for a very fluid and interactive experience. Express is used for developing back-end services, or APIs, for single-page applications to fetch data.

2. Real-time applications

Real-time applications are increasingly popular as they allow users to interact with each other in real time. Some popular examples of real-time applications include multiplayer games, chat apps, and collaboration tools. Express is used in developing real-time applications.

It helps you build the basic structure, like handling web pages and buttons, and when you want your website to instantly update without needing to refresh the page, Express.js and can work together.

Express.js can take care of the regular stuff your website needs, like showing pages and handling regular requests. While WebSockets enables real-time data exchange between the server and clients.

3. Streaming applications 

Streaming applications are becoming increasingly popular as they allow users to watch movies, TV shows, and other content on demand. Some popular examples of streaming applications include Netflix, Hulu, and Disney+.

You can leverage Express in streaming applications for a variety of tasks, including handling requests, serving media files, developing authentication and authorization modules, implementing search and recommendations, and many more functionalities.

4. Fintech application

Some popular fintech applications that are built with Express.js include Robinhood, Coinbase, and PayPal. Leveraging the robust functionalities of Express.js, these applications efficiently manage intricate financial transactions.

5. APIs

APIs are software intermediaries that allow different systems to communicate with each other. They are widely utilized by different systems for integrating payment gateways, social media integrations, and e-commerce integrations. Brillworks has developed a suite of APIs and applications for the business consulting and media preservation industries, which includes critical functions such as company setup, visa services, corporate services, file management, customer portal, CMS portal, bulk upload, etc.

Why Learn Express?

Flexible and Fast

Express.js is a flexible framework that lets developers do their thing. You can mix and match middleware, pick your favorite templating engines, and even choose databases that fit your project. It's like having a toolbox of tools at your disposal.

For example, if you need to build a real-time app, you can use Express.js with middleware like to add real-time functionality to your app. Or, if you need to build a single-page app, you can use Express.js with a templating engine like Pug to render your HTML views.


It is lightweight and easy to use. It gives developers a lot of control over the architecture of their applications, which can be helpful for building customized and complex applications.

Easier Learning curve

If you're already familiar with JavaScript and web development, it will be a smooth journey. But if you're new to web development or backend frameworks, it might be a bit steeper.

Express is built on top of Node.js, so if you know Node.js, you're already a step ahead. Express is also very minimalistic and has a clear structure, which makes it easy to grasp for developers who are already comfortable with server-side concepts.

But even if you're new to web development, there are plenty of tutorials, documentation, and community support available to help you learn Express.

Community Support

If you are a beginner or a company that is looking for a well-established tool for backend development, it is essential to check if the framework or technology stack that you are going to choose has decent community support and is well-tested. Moreover, there are other factors that you should consider.

A strong community means that there are plenty of people who are using and supporting the framework, which means that you'll be able to get help if you need it. Express is the most popular nodejs framework, which we have already covered in another post

Example of Creating a Web Server Using Express

Here's a basic example of how you can create a simple web server using Express.js, a popular Node.js web application framework:

1. Make sure you have Node.js and npm (Node Package Manager) installed on your machine. You can download them from 

2. Create a new directory for your project and navigate to it using your terminal.

3. Initialize a new Node.js project by running the following command and following the prompts:

npm init

4. Install Express as a dependency for your project:

npm install express

5. Create a file named app.js (or any other name you prefer) in your project directory.

6. Open app.js in a text editor and add the following code:

// Import the Express module

const express = require('express');

// Create an instance of the Express application

const app = express();

// Define a route for the root URL

app.get('/', (req, res) => {

  res.send('Hello, World!');


// Start the server on port 3000

app.listen(3000, () => {

  console.log('Server is listening on port 3000');


7. Save the file and return to your terminal.

8. Run the Express server by executing the following command:

 node app.js

9. You should see the message "Server is listening on port 3000" printed in your terminal.

10. Open your web browser and navigate to http://localhost:3000 . You should see the "Hello, World!" message displayed in your browser.

11. Congratulations! You've just created a basic web server using Express.js.


In the dynamic landscape of web development, Express.js shines as one of the most popular and powerful frameworks for building back-end applications. This article has served as your gateway to understanding the essentials of Express.js, explaining its significance and benefits in the nodejs development world.

Whether you're upgrading existing systems or starting from scratch, we've got you covered. Our skilled Express team can help you develop APIs, web apps, and services tailored to your needs. Do you want to scale up your Back-End? Hire Express Developers Today.

Lavesh Katariya

Lavesh Katariya

With over 8 years of experience in the MERN stack, I specialize in building robust and scalable web applications. Proficient in MongoDB, Express.js, React.js, and Node.js, my passion for clean code and innovative problem-solving ensures high-quality solutions.

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