Web Development

What Is the MERN Stack? Introduction and How it Works

Published: 9th May, 2023

Arunav Goswami

Web Development Consultant at almaBetter

Discover the power of MERN stack, a full-stack JavaScript framework for building modern, scalable web applications. Learn about its components and how they work together.

In today’s fast-paced world, where businesses rely heavily on efficient and visually appealing web applications, the demand for developers with a solid understanding of modern web development technologies has never been higher. Enter the MERN stack, a powerful and popular tech stack that has taken the world of web development by storm. This article will explore the intricacies of the MERN stack, demonstrating how its components work together to create scalable, robust, and engaging web applications.

What is MERN Stack?

MERN is an acronym for MongoDB, Express, React, and Node.js. These four technologies combine to create a full-stack JavaScript framework that enables developers to build highly efficient, user-friendly, and dynamic web applications from scratch. Let’s dive deeper into each component and understand their role in this powerful stack:


MongoDB is a NoSQL, document-oriented database designed for scalability and flexibility. Unlike traditional relational databases, MongoDB stores data in BSON format, a binary representation of JSON. This makes it easier to manage large volumes of data with complex and nested structures. MongoDB offers features such as horizontal scaling, automatic sharding, and strong consistency, making it an ideal choice for modern web applications.


Express is a minimal, unopinionated, and flexible web application framework built on top of Node.js. It simplifies the process of building web applications by providing essential features such as routing, middleware, and API handling. Express offers a robust foundation for creating RESTful APIs, single-page applications, and multi-page applications, making it a versatile choice for a variety of projects.


React, developed and maintained by Facebook, is a popular JavaScript library for building user interfaces. Its primary goal is to make the development of complex UI components more manageable, efficient, and maintainable. React’s core principle is the use of components and reusable pieces of UI that can be combined to build a full application. It utilizes a virtual DOM, which optimizes the rendering process and improves application performance. React’s popularity and community support have made it the go-to library for front-end development.


Node.js is an open-source JavaScript runtime environment built on Chrome’s V8 JavaScript engine. It allows developers to run JavaScript code on the server side, opening up a world of possibilities for full-stack JavaScript development. Node.js is known for its event-driven, non-blocking I/O model, which makes it highly efficient in handling concurrent requests and real-time applications.

The Working

MERN stack architecture

The MERN stack combines MongoDB, Express, React, and Node.js to create a full-stack JavaScript framework for building web applications. Each component plays a specific role in the development process. Let’s break down how the MERN stack works by examining the role of each component and how they interact with one another.

  • A user interacts with the web application’s UI, which is built using React components.
  • React captures the user interaction and updates the application state if necessary.
  • If the interaction requires data fetching or updating, React sends an API request to the Express server.
  • Express processes the API request and communicates with MongoDB to perform the required data operations.
  • MongoDB stores, retrieves, or updates the data as needed, and the result is sent back to Express.
  • Express sends the response back to React, which updates the UI accordingly.
  • This seamless interaction between the frontend (React) and backend (Express, MongoDB, and Node.js) is what makes the MERN stack a powerful and efficient framework for building modern web applications.
  • Deploying Your MERN Stack App on Heroku

Screenshot of Heroku

In the fast-paced world of Web Development, you need a reliable, efficient, and seamless deployment process. Heroku, a cloud platform-as-a-service (PaaS), offers the perfect solution. With its user-friendly interface and robust infrastructure, deploying your MERN stack application on Heroku becomes a walk in the park. Let’s explore a concise yet informative guide to getting your MERN stack app live on Heroku:

Sign Up and Set Up: Register for a Heroku account and install the Heroku CLI on your machine, ensuring you have the necessary tools to initiate deployment.

Procfile Creation: Craft a ‘Procfile’ in your application’s root folder, providing Heroku with essential instructions on how to run your app.

Start Script Addition: Define a ‘start’ script within your ‘package.json’ file, specifying the command that launches your application.

Dynamic Port Configuration: Adjust your server file to use ‘process.env.PORT’ for dynamic port assignment, ensuring seamless integration with Heroku’s environment.

Git Repository Initialization: Create a Git repository in your project folder and commit all changes, preparing your app for deployment.

Heroku Login: Connect to your Heroku account via the CLI, establishing a link between your local machine and the Heroku platform.

Heroku App Creation: Generate a new Heroku application, reserving a dedicated space in the cloud for your app.

MongoDB Add-on Integration: Implement a MongoDB add-on, such as ‘mLab MongoDB’, to provide a cloud-based database solution for your MERN stack application.

Database Connection Configuration: Modify your app to utilize the MongoDB URI supplied by the add-on, establishing a connection to your new cloud-based database.

Code Deployment: Push your code to the Heroku remote repository, initiating the automated build and deployment process.

Open your deployed application in the browser and enjoy the fruits of your labor. Your MERN stack app is now live on Heroku!

Why Choose MERN Stack?

Full-Stack JavaScript: MERN stack allows developers to use JavaScript throughout the entire development process. This means a more streamlined and consistent workflow, reduced context switching, and easier communication among team members.

Scalability and Performance: MERN’s components are designed for scalability and high performance, making it suitable for web applications with heavy traffic and demanding workloads.

Large and Active Community: The MERN stack enjoys an extensive, active, and supportive community, which means access to a plethora of resources, libraries, and tools that can simplify and speed up development.

Flexibility and Modularity: MERN components are modular and can be easily integrated with other technologies, allowing developers to customize their tech stack according to project requirements.


The MERN stack, with its powerful combination of MongoDB, Express, React, and Node.js, has become a go-to choice for developers looking to build modern, scalable, and engaging web applications. Its full-stack JavaScript nature, flexibility, and strong community support make it a compelling choice for projects of any scale. In the ever-changing landscape of web development, the MERN stack is well-positioned to lead the charge as a trailblazer among state-of-the-art technologies. Furthermore, deploying a MERN stack application on Heroku is a simple and efficient process, making it an ideal choice for developers looking to get their projects up and running quickly.

Join AlmaBetter’s Full Stack Web Developer course to learn more about MERN & deployment.

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