Ciprian Craciun - FrontEnd Developer

Ciprian Craciun

FrontEnd/Web Developer

Engineering is about making a product better, learning from past mistakes and create a process which is easy for all to understand.

Chrome Extension Development: Building Your First Extension in Simple Steps

If you are a Google Chrome user, you have likely come across various extensions that enhance the functionality of your browser. Have you ever wondered how to build your own Chrome extension? In this comprehensive guide, we will walk you through the process of creating a Chrome extension from scratch. Whether you want to automate repetitive tasks or add new features to your browsing experience, creating a Chrome extension can provide a solution.

Understanding Chrome Extensions

Before diving into the technical aspects of building a Chrome extension, it’s important to understand what exactly a Chrome extension is. A Chrome extension is a program installed in the Chrome browser that modifies its functionality. It is built using web technologies such as HTML, CSS, and JavaScript, similar to developing a web application. However, a Chrome extension requires a manifest.json file, which we will discuss in detail later.

Chrome extensions can be powerful tools that enhance your browsing experience. They can automate tasks, modify existing behaviors, and improve convenience. With Chrome extensions, the possibilities are endless.

Benefits of Building a Chrome Extension

Before we delve into the step-by-step process of creating a Chrome extension, let’s explore some of the benefits of building one:

  • Increased Productivity: Chrome extensions can automate repetitive tasks, saving you time and effort. By building your own extension, you can tailor it to your specific needs and streamline your workflow.
  • Customizability: With a Chrome extension, you have the freedom to customize your browsing experience. You can add features and functionalities that are not available in the default browser settings.
  • Seamless Integration: If you have a web application or a SaaS product, a Chrome extension can serve as an excellent addition. It allows you to provide a seamless experience for your users and extend the functionality of your product.
  • Learning Opportunity: Building a Chrome extension is a great way to learn new technologies and improve your coding skills. It provides hands-on experience with web development and allows you to explore different APIs offered by Google Chrome.

Now that we understand the benefits of building a Chrome extension, let’s dive into the step-by-step process.

Setting up the Project

To begin creating your Chrome extension, you need to set up a project folder. Create an empty folder on your computer where you will store all the necessary files for your extension. Give it a meaningful name that represents your project.

Creating the Manifest File

The manifest file is a crucial component of a Chrome extension. It contains metadata about the extension, such as its name, version, and permissions.

manifest json

In the above image, you specify the basic information about your extension, such as its name, version, and description. You also define the permissions required for your extension to function properly and specify the icons that will be displayed.

Let’s see line by line what we have in the manifest file.

  • manifest_version: should be set to 2 because form January 2014 Chrome dropped the support for version 1;
  • name: it’s referring to the name of the extension;
  • version: is the extension version, if you release something and you do some updates, you need to update the version;
  • description: add what is supposed to do your extension;
  • permissions: this is an important tag because here we add the most important permissions from Chrome API’s, you can see some of them on the official site;
  • background: this attribute is referring to the first script which is running in the background when you open or install the extension. I will show you an example later in this tutorial.
  • browser_action: is supposed to show you the default extension icon and you also can add a default HTML template, as I added in my case, but you can add more options, check chrome API.
  • icons: for this tag, I added a set of images to serve me a good resolution on different devices.

Because we defined some important attributes in our manifest.json file, now we need to create background.js and popup.html files at the root of the project. So before diving further, I suppose you created a project folder for your Chrome extension and then add the manifest.json file with the required files. Click on Load unpacked button and open your project folder, you will load your first Chrome extension.

how to load a chrome extension

Introduce User Actions

This should be the latest step from creating a basic extension. As I said before we have background.js file which can be very simple:


If you click on the background page link from the extension you will have a Chrome console open with some messages or the code you need on the first load.

chrome logs

As we can see in the next image, popup.html has some HTML code where we declare a button for user interaction.

html template for extension
HTML template

Now the fun part for this is to add a new file popup.js, where we can add the logic for the Chrome extension.

page speed API request

Start with document.addEventListener(‘DOMContentLoaded’ , callback), this means when all of the HTML is ready to interact with then we can add our logic:

  // create a form 
  const form = document.createElement('form');
  form.action ='';
  form.method = 'post';
  const input = document.createElement('input');
  input.type = 'hidden'; = 'url';

We create with javascript a form with a hidden input where we try to append the current URL tab of the Chrome page to the page speed API, on the next step, we get the URL tab on the click event.

// on click event
  checkPageButton.addEventListener('click', function () {
    chrome.tabs.query({ currentWindow: true, active: true }, function (tabs) {
      // set the url of current tab
      input.value = tabs[0].url;
      const newUrl = form.action + '?url='+ tabs[0].url;
      form.action = newUrl;
  }, false);

As we can see in the above code, on the click event we get the URL tab by consuming chrome tabs API and we append it to the form action. When you will click on the “Test btn” from the chrome extension you will send a POST request to the page speed API.

This is just an example to see how you can build a simple Chrome extension but the logic can be extended and improved by your needs. For example, instead of creating a form and attaching the URL to the action, you can use an XHR request to send and get some responses from page speed API.

Some links that I used to develop a Chrome extension:

Testing and Debugging

Testing and debugging are crucial steps in the development process of any software, including Chrome extensions. It’s important to ensure that your extension works as expected and doesn’t cause any issues or conflicts with other extensions or browser functionalities.

To test your Chrome extension, you can load it as an unpacked extension in your Chrome browser. Open the Extensions page in Chrome (chrome://extensions/), enable the “Developer mode” option, and click on “Load unpacked” to select your project folder. This will load your extension into Chrome, allowing you to test its functionality.

While testing, pay attention to any error messages or unexpected behaviors. Use the Chrome DevTools to debug your extension and fix any issues that arise. The DevTools provide a set of powerful debugging tools that can help you identify and resolve problems.

Publishing Your Extension

Once you are satisfied with the functionality and stability of your Chrome extension, you can consider publishing it to the Chrome Web Store. Publishing your extension allows users to discover and install it directly from the store.

To publish your extension, you need to create a developer account on the Chrome Web Store and pay a one-time registration fee. After that, you can upload your extension package, provide the necessary details and screenshots, and submit it for review. Once approved, your extension will be available for users to install and enjoy.

Updating and Maintaining Your Extension

Building a Chrome extension is not a one-time task. It requires ongoing maintenance and updates to ensure compatibility with new browser versions and to fix any bugs or issues that may arise. It’s important to stay up to date with the latest changes in the Chrome extension ecosystem and make necessary updates to your code.

Regularly check for updates to the Chrome extension APIs and make any required changes to your code. Test your extension on different versions of Chrome to ensure compatibility. Listen to user feedback and address any reported issues promptly.

Promoting Your Extension

Once your Chrome extension is published and available in the Chrome Web Store, you can promote it to reach a wider audience. Here are a few strategies to promote your extension:

  • Optimize the Listing: Create an appealing and informative listing page for your extension in the Chrome Web Store. Use relevant keywords, add screenshots and videos, and provide a compelling description to attract users.
  • Leverage Social Media: Use social media platforms to promote your extension. Share updates, tutorials, and tips related to your extension to engage with your target audience.
  • Collaborate with Influencers: Partner with influencers or bloggers in your niche who have an audience interested in your extension. Collaborate on content or offer them exclusive features to promote your extension to their followers.
  • Reach Out to Publications: Contact technology publications or blogs that cover Chrome extensions and offer them a review or feature article about your extension. This can help generate buzz and attract new users.
  • Engage with the Community: Participate in forums, communities, and discussion boards related to Chrome extensions. Answer questions, provide helpful tips, and promote your extension when appropriate.

By following these promotion strategies, you can increase the visibility and usage of your Chrome extension.


Building a Chrome extension can be a rewarding experience, allowing you to customize your browsing experience, automate tasks, and even create a product that adds value to users. By following the step-by-step process outlined in this guide, you can create your own Chrome extension and unleash its potential.

Remember to continuously update and maintain your extension, listen to user feedback, and promote it effectively to reach a wider audience. With dedication, creativity, and a solid understanding of Chrome extension development, you can build a successful extension that enhances the browsing experience for users around the world.

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