Wednesday, April 24

Headless Browser: What Is It And How It Works?

All internet technologies have improved a lot in the past two decades, including web development. Ever since the internet became commercially available, developers have improved their user experience. More specifically, internet users today have many different options on how to browse the web. 

One of the latest technologies in this domain are headless browsers. In 2009 Google stated that these browsers have the power to help improve indexing with a variety of different websites. On top of that, headless browsers can help with user experience testing.

But we’re getting ahead of ourselves. The critical thing to remember is that both Firefox and Chrome have versions that support headless flags, which means that this approach is gaining traction and will be much more approachable in the future. 

What is a headless browser? 

The name for these browsers comes from their fundamental design – they don’t have a user interface. Simply put, these browsers let users visit a web page, but the whole graphic user interface is concealed. These browsers are similar to mainstream browsers people use today. 

However, users don’t have a graphic representation on their screens. The whole process is happening in the backend without anything shown on the screen. These browsers can do all the functions like a regular browser, including uploads, downloads, navigation, clicking on links, and so on. 

But the difference is that we cannot do these tasks by using an interface and clicking on actions. Instead, all of the commands are done sequentially. All of this is done through a command console, and users can also track all the processes. 

How headless browsers work 

Headless browsers understand and render HTML just like any other browser. They can also interpret web pages without any issues. They can also parse pages and JavaScript, and that’s why they can support functionalities like downloads or using links. 

Simply put, they have the same fundamental infrastructure as other browsers but without the graphical side of user experience. One of the key advantages of this approach is that there are no heavy memory and speed costs associated with GUI that regular browsers have. 

That’s why headless browsers aren’t for anyone. However, these things bring a lot of advantages for performing a variety of different tasks. 

Apart from better performance, these browsers also give greater stability essential for different business and development applications. That’s why headless browsers are most commonly used for “testing” sites in various ways. 

Use cases for headless browsers 

All of the everyday actions internet users do on websites are ideal for testing with headless browsers. Whenever a user interacts with something on a web page, clicks on something, types something, or downloads, there are backend functions set in motion that execute their actions. 

All these functions can go wrong, fail to execute, or work slower than they should. In web development, it’s essential to test out all these functions before going live. Sometimes, you need to run several tests in a stable environment to determine the root cause of the problem. 

That’s why headless browsers are great for testing out these aspects of a website: 

  • Basic flows 
  • Alternative (complex) flows 
  • Website form submission and filling 
  • SSL functionality 
  • Testing how the site works with different server loads 
  • Checking out the response time of a certain page 
  • Extracting (scraping) data from the website 

How to find the right one for your needs

There are many different types of websites today. They are all designed for different things and provide certain user experiences to their visitors. That’s why different sites might need different functionalities and, therefore, different types of tests. 

Developers need a headless browser that can test everything they need while at the same time giving good speed and stability. Some people also decide to go the route of using a proxy, which you can learn more about in detail on Geonode Proxies.

Here are some of the most popular headless browsers and what they are used for so that you can pick the one best for your needs.

  • Chrome

Google Chrome has a “headless mode” that simulates headless browsing with lower memory requirements. This option comes with various tools useful for tasks like creating PDF documents, taking screenshots, extracting information, and navigation testing. 

  • Firefox 

Mozilla also has a headless mode for its browser. It allows users to simulate different browsers using W3C WebDriver, Slimmer JS, and Selenium API – it’s great for unit testing, scripting, testing flows, and automation. 

  • HtmlUnit

This browser is entirely written in Java, meaning that it has a wide range of testing available for commercial websites. That includes all HTTP testing, such as the performance of headers, pages, or authentication. It’s also good for testing links, redirects, and website forms. 


We hope this article has helped you get a general idea about what is a headless browser. A business can perform all of the tasks mentioned in a much more efficient manner than traditional methods. That’s why many expect these browsers to become a standard in different fields. 

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