Create a Chrome extension from scratch step-by-step (2025)

Summary:

Discover the essentials of Chrome extension development with our detailed guide, which covers every stage from the initial concept to the final deployment. This comprehensive approach includes defining objectives, designing the user interface, implementing functionalities, and integrating APIs.

It’s essential to understand not only how to build Chrome extensions but also to adhere to best practices for security as you embark on this journey. To exemplify the practicality of these steps, we will showcase how Creole Studios, as a Chrome extension development company, developed the “Enrolup” Chrome extension.

Introduction:

Chrome extension development has revolutionized web interactions, particularly for small business owners, offering personalized tools that optimize tasks, integrate services, and tailor web pages. This customization boosts productivity and streamlines workflows, presenting a powerful symbiosis between Chrome extensions and business operations.  If you’re looking to create Chrome extensions to enhance your business capabilities, this guide will walk you through the essential steps.

By learning how to create a Chrome extension, you can leverage this technology to improve user experiences and streamline operations. For example “Enrolup – Chrome extension” is a valuable tool for universities developed by Creole Studios. It enables them to understand the limitations they might have on the course offering page of their website. It helps and suggests how can they improve their page conversion and increase user engagement, leading to a higher rate of course enrollment and success.

What is Chrome Extension?

A Chrome extension is a small software program designed to add specific features or functionality to the Google Chrome browser, enhancing the user’s browsing experience. Developed using web technologies like HTML, CSS, and JavaScript, these extensions can interact with web pages and browser functions, allowing users to customize and improve how they navigate the web.

Extensions can range from simple tools that modify webpage content to complex applications that integrate with external services or provide advanced features. For instance, an extension might add new buttons to the browser, change the appearance of a website, or offer new functionality like improved security, productivity tools, or enhanced user interaction.

Reasons to Create a Chrome Extension

1. Low Barrier to Entry

Creating a Chrome extension is an accessible starting point for aspiring developers and entrepreneurs. Unlike building a full-fledged software product, you don’t need an extensive budget, a large team, or advanced development skills to get started. With basic coding knowledge and a solid idea, you can develop a Chrome extension on your own.

2. Fast Development and Launch

Compared to other software, Chrome extensions are quicker to develop and bring to market due to their relatively straightforward functionality. Chrome’s robust development environment and detailed documentation enable streamlined planning, coding, and deployment, making it faster to release your extension to users. Once launched, you can start monetizing your extension sooner than you would with a more complex software product, allowing you to gauge interest and potentially generate revenue early on.

3. Effective Tool for Testing Product-Market Fit

If you have a broader product idea, creating a Chrome extension is an efficient way to test its appeal with minimal investment. Launching a streamlined version of your concept as an extension lets you validate if there’s demand for your solution. If users find value in your extension, it’s a positive sign to consider developing a more comprehensive app.

4. Additional Channel for Brand Visibility and Promotion

If you already have a product, a complementary Chrome extension can serve as an additional marketing tool. Being listed on the Chrome Web Store increases your visibility to new users, much like being on a major e-commerce platform. A well-designed extension can attract users who may later explore your main product.

Chrome Extension Development Steps

Step 1: Define Objectives and Features

• It involves several crucial steps to build Chrome extensions. When aiming to create the best Chrome extension, start by clearly defining your objectives and features, it’s crucial to have a clear vision of what you want to achieve and how the extension will serve its users when you develop Chrome extensions.

Objective’s Enrolup extension: 

• Tool for universities and education providers to show how to improve conversions for course website pages.
• Enables users to analyze an unlimited number of course website pages for their conversion potential.

Step 2: Create the Project Structure

• Create a new folder for your extension and organize it with the necessary files. When you start to build Chrome extensions, this step is vital for maintaining an organized and manageable project. Required files include manifest.json, popup.html, popup.js, background.js, and any other assets or scripts.
• Required files include manifest.json, popup.html, popup.js, background.js, and any other assets or scripts.

Structure for Enrolup extension:

• To keep our development organized, we set up a new project folder named “EnrolUpExtension.” This folder contained all extension files and assets.

Inside the folder, we created the following files:

1. manifest.json: This file held critical information about the extension, including its name, description, version, permissions, and icons.
2. popup.html: We designed the user interface for the extension’s popup, where users accessed course recommendations and other details.
3. popup.js: The JavaScript code was implemented to handle the functionality of the popup.
4. background.js: We developed the background script responsible for handling events and interactions that occurred in the background.

Step 3: Manifest File

• In the “manifest.json” file, specify essential metadata, such as the extension’s name, description, version, and icons.
• Declare the necessary permissions for the extension’s functionality, such as accessing web pages or data.

Manifest file for Enrolup extension:

• In the “manifest.json” file, we defined the necessary metadata for the extension, such as the name, description, version, and icons.
• Next, we specified the required permissions, including access to web pages and data, essential for the extension’s functionality.
• We set up the browser_action property to define the appearance and behavior of the extension’s browser action, i.e., the popup.
• Finally, we included the background script to enable communication between the popup and the background.

{
"manifest_version": 3,
"name": "QuickInsights Research Assistant",
"short_name": "qi-assist",
"version": "1.0.0",
"description": "QuickInsights: Simplify research with AI summaries, customized prompts, and efficient reporting.",
"icons": {
"16": "assets/quickinsights/qi-16.png",
"32": "assets/quickinsights/qi-32.png",
"48": "assets/quickinsights/qi-48.png",
"128": "assets/quickinsights/qi-128.png"
},
"permissions": [
"activeTab",
"tabs",
"webNavigation"
],
"action": {
"default_title": "Get Insights"
},
"background": {
"service_worker": "background.js",
"type": "module"
},
"host_permissions": ["<all_urls>"],
"content_security_policy": {
"extension_pages": "script-src 'self' 'wasm-unsafe-eval'; object-src 'self'; frame-src 'self'"
}
}

Step 4: Designed the Popup User Interface

• When making a Chrome extension, designing an intuitive and user-friendly popup interface is crucial for a positive user experience using HTML and CSS in the “popup.html” file. Customizing the popup’s appearance to match your extension’s branding is key when you create Chrome extensions. Ensure it’s visually appealing and functional.
• Customize the popup’s appearance to match your extension’s branding.

Interface Enrolup extension:

• At Creole Studios, we designed an intuitive and visually appealing popup interface for the EnrolUp Chrome Extension.
• JavaScript code was implemented in the “popup.js” file to add functionality to the popup.
• We utilized event listeners to handle user interactions, such as button clicks or form submissions within the popup.
• The pop-up served as the gateway for users to access essential features, including course recommendations, university ratings, program details, and user reviews.

Step 5: Implemented Popup Functionality

• Write JavaScript code in the “popup.js” file to handle user interactions and fetch data if required. Effective implementation of popup functionality is essential while you build Chrome extensions that is both useful and engaging
• Ensure the popup’s functionality aligns with the extension’s objectives.

Popup for Enrolup extension:

• In the “popup.js” file, we wrote JavaScript code to fetch and display course recommendations and related data from the universities’ databases or APIs.
• To enhance user interactions, we implemented features such as filtering courses, sorting options, and the ability to view more details for each course.
• We ensured a seamless user experience by handling errors gracefully and providing helpful messages when necessary.

Step 6: Background Script Functionality

• Create the “background.js” file to handle events and interactions that occur in the background. This script is important for managing tasks beyond the popup’s scope when you create Chrome extensions
• Set up communication between the popup and the background script if needed.
• Depending on your extension’s requirements, you can include additional features like context menus, notifications, or browser actions.

Setting Up Welcome and Thank You Pages on Extension Install and Uninstall

When the extension is installed or uninstalled, we can trigger the background.js file to open welcome and thank-you pages:

chrome.runtime.onInstalled.addListener((details) => {
if (details && details.reason === chrome.runtime.OnInstalledReason.INSTALL) {
chrome.tabs.create({ url: "your-welcome-page-url" });
}
});
chrome.runtime.setUninstallURL("your-thank-you-page-url")

Scripting for Enrolup extension:

• To create a seamless experience, we leveraged the “background.js” file as the backbone of the EnrolUp Chrome Extension’s functionality.
• The background script ran continuously in the background, managing events and interactions beyond the scope of the popup.
• It facilitated communication between the popup and content scripts, ensuring seamless data exchange and action coordination.
• The background script also handled background tasks, such as periodically updating the extension’s data and managing user preferences through the Chrome storage API.
• By employing the background script, the EnrolUp Extension delivered a consistent and reliable user experience, even when the popup was closed or not in focus.

Step 7: Integrate APIs and Databases (if applicable)

• If your extension needs to fetch real-time data, integrate APIs or databases accordingly.
• Implement mechanisms to update the extension’s data periodically.

API’s for Enrolup extension:

• Currently, we have not done any API Integration. To ensure real-time data availability, we can integrate APIs or databases from universities to fetch course and program information if required.
• We implemented mechanisms to update the extension’s data periodically, ensuring that the information presented was up-to-date and accurate.

Step 8: Tested and Debugged

• Thoroughly test your extension on various web pages and scenarios to ensure it functions correctly.
• Debug any issues or errors that arise during testing.

Testing of Enrolup extension:

• Thorough testing was crucial to create a reliable extension. We tested the EnrolUp Chrome extension on various web pages and scenarios to ensure it functioned correctly.
• In the testing phase, we also debugged any issues or errors that arose, making the extension stable and dependable.

Step 9: Optimized Performance

• Optimize your extension’s code and assets to ensure smooth performance and fast loading times. Performance optimization is essential to prevent any negative impact on users’ browsing experience when you create Chrome extensions.
• Minimize the use of resources to prevent any negative impact on users’ browsing experience.

Optimization of Enrolup extension: 

• For a seamless browsing experience, we optimized the extension’s code and assets to ensure smooth performance and fast loading times.
• Minimizing the use of resources prevented any negative impact on users’ browsing experience.

Step 10: Publish Chrome extension on Chrome Web Store (Optional)

• If you wish to make your extension available to a wider audience, you can publish Chrome extension on the Chrome Web Store. Following the submission guidelines and review process will help you build Chrome extensions that reach more users.
• Follow the submission guidelines and review process to get your extension approved.

Publishing of Enrolup extension:

• For the EnrolUp extension, once it was fully developed, we packaged it into a zip file. We then uploaded it to the Chrome Web Store for review, following all necessary steps to publish Chrome extension successfully.
• We uploaded the extension to the Chrome Web Store for review and publication, making it accessible to a broader audience.

Read more: Top 10 Tips for Chrome Extension Development

Conclusion:

In conclusion, Chrome extension development is an exciting and rewarding journey that allows developers to create powerful tools and enhance the browsing experience for millions of users. With our step-by-step guide and the essential steps, we hope you have a clear roadmap to embark on your extension development project. When you aim to create Chrome extensions each step requires careful execution. As a Chrome extension development company, we would emphasize that each step needs utmost attention and review.

FAQs

Can you create your own Chrome extension?

Yes, anyone with knowledge of web development can create their own Chrome extension using HTML, CSS, and JavaScript.

How much does it cost to create a Chrome extension?

The cost varies depending on complexity and features, basic extensions can be developed with minimal costs, while advanced ones may require a larger budget

How hard is it to create a Chrome extension

Creating a basic Chrome extension is relatively straightforward if you’re familiar with web technologies. More complex extensions may require advanced programming skills.

How much time does it take to build a chrome extension?

Development time depends on the extension’s complexity. Simple extensions can take a few hours to a few days, while complex ones may take several weeks.

What language are chrome extensions written in?

 Chrome extensions are primarily written in HTML, CSS, and JavaScript, with options to use additional technologies for more advanced functionality.

Does it cost money to publish a Chrome extension?

Yes, there is a one-time $5 developer registration fee to publish on the Chrome Web Store. 

Chrome Extension

Bhargav Bhanderi

Director - Web & Cloud Technologies