What is a Headless Browser?

Adelina Kiskyte

Last updated by Akvilė Lūžaitė

2025-07-15

5 min read

A headless browser is a web browser that operates without a graphical user interface (GUI). It allows automated interaction with web pages in a way that mimics standard browsers, but it's controlled through a command-line interface or network communication.

In this article, you will learn what a headless browser is, what it is used for, what is headless Chrome, and what other browsers are most popular in headless mode. We will also discuss the primary limitations of headless browser testing.

For your convenience, we also have this topic covered in a video format:

What is a headless browser?

Headless browser is a web browser that is not configured with a Graphical User Interface (GUI). It is mostly used by software test engineers, because browsers without a GUI perform faster since they do not have to draw visual content. One of the largest benefits of headless browsers is their ability to be run on servers without GUI support.

Headless browsers are usually executed via command line, or via network communication.

What is a headless browser used for?

The most common use case for headless browsers is web page testing. Headless browsers easily understand HTML pages and interpret them as any other browser. They depict style elements, including colors, fonts, layouts, etc. This makes headless browsing a valuable tool for developers focused on rendering accuracy without launching a full browser.

So, what is the use of headless browser testing?

Automation

Headless browsers are used for automation testing in order to check submission forms, mouse clicks, keyboard inputs, etc. Basically, it includes anything that can be automated to save time and effort in any part of the software delivery cycle, including development, quality assurance, and installation. Automated browser tests can also be run for JavaScript libraries. These tests run faster and more efficiently when using a headless browser environment that removes the overhead of the user interface.

Layout testing

Headless browsers can render HTML and load CSS elements just like a real browser. They are used for layout checks, for example to determine the default page width and element coordinates. This makes them well-suited for testing web applications across different layouts and screen sizes. Headless browser testing also allows color selection testing for various elements. JavaScript and AJAX execution can be tested as well. Developers often automate screen captures in headless browsers in order to test the layout. This supports test execution across environments and enables easier comparison across different UI states.

Performance

Website performance can be quickly tested using a headless browser. Since a browser without GUI loads websites much faster, performance testing tasks that do not require user interface interaction can be tested via the command line. In such tasks, there is no need to manually refresh pages. While this saves time and effort, it is important to note that only small performance testing tasks such as log-in tests can be examined with a headless browser. However, for broader performance coverage and test reliability, cross browser testing may be needed in parallel.

Data extraction

When it comes to web scraping and data extraction with a headless browser, there is often no need to start a website. Web scraping with a headless browser allows quickly navigating websites and collecting public data. This includes handling user interactions, executing dynamic content loading, and adapting to JavaScript-rendered elements during extraction.

Oxylabs' Web Scraper API and Web Unblocker have a Headless Browser feature, enabling users to gather public data from complex targets. This feature allows you to:

Configure browser instructions to automate user interactions
Customize browser behavior to simulate an organic user
Execute JavaScript and load more data onto the page

Your scraping operations will be better equipped to handle various page interactions and challenges without relying on external tools.

Most popular headless browsers

One of the main requirements for headless browsers is to be able to run on low resources. The browser should run in the background without significantly slowing down other tasks being performed by the system. This is particularly valuable in CI/CD environments, where fast test execution is prioritized.

Different headless browsers perform better in different testing scenarios. For this reason, developers often have to test various options to find the best combination of tools for their case. Here are some of the most popular headless browsers and their main features:

Google Chrome can run in a headless environment and provide a regular browser context without using up as much memory. Google Chrome headless mode is available in version 59 or higher. The most common tasks performed in Headless Chrome include printing the Document Object Model (DOM), creating a PDF, and taking screenshots. Check out our guide on How to Use Chrome Browser Proxy Settings.
Mozilla Firefox in headless mode can be connected to different APIs – check out our blog post on what are APIs and how they would be useful for you. The most popular framework to use with Firefox is Selenium. Headless Firefox is mostly used for running automated tests as it makes the testing process more efficient.
HtmlUnit is written in Java and used to automate different ways in which users interact with websites. This headless browser is most popular for testing e-commerce websites as it is best for testing submission forms, website redirects, and HTTP authentication. It offers a strong environment for simulating complex user interactions.

Phantom JS is also worth mentioning because it used to be a popular headless web browser. Many developers have compared PhantomJS vs HtmlUnit. However, Phantom JS has been discontinued for a few years now. It was open-source, supported by contributions from dedicated developers.

What is headless testing?

Headless testing is the process of performing browser tests without the type of browser UI or GUI. This means that while this technique tests the components, it skips the part associated with rendering visual elements.

One of the essential reasons for carrying out headless browser testing is its ability to run tests faster in a real browser environment. However, while headless testing enables quicker, easier, and less resource-intensive automation, it also has its own limitations that we recommend to always keep in mind.

Headless browser testing: limitations

Headless testing has its limitations. Here are some examples:

Running tests with headless browsers may shift developer's attention towards fixing bugs that only appear when using browsers in a headless environment. However, it is important not to forget that users will hardly ever visit the website with a headless browser. So focusing on issues that appear on a full browser should be a priority. These bugs might stem from how the browser loads assets or handles layout rendering, and must be evaluated alongside broader testing goals.
During headless testing, some pages load too fast, making it difficult to debug inconsistent failures on locating elements. This kind of limited testing might obscure real user behaviors, requiring fallback to manual or GUI-based tests. Cross browser testing, which involves running tests across different browser versions, can help resolve these inconsistencies and ensure more robust coverage following major code changes.

Conclusion

Headless browsers work much faster than regular browsers, since they do not have to load all the content that contributes to user experience.

Due to their high speed, headless browsers are often used for web page testing. They are employed in testing various automation tasks on a website, its performance, and layout. Data extraction is another common use case for headless browsers.

Some of the most popular web browsers, including Chrome and Mozilla Firefox come in headless mode.

However, headless browsers also have limitations and in some cases testing should be performed in regular browsers.

If you would like to learn more about web scraping and data gathering with a headless browser, read our blog post – Web Scraping With Selenium: DIY or Buy? Also, check out our Residential Proxies that are irreplaceable for any web scraping project.

Frequently asked questions

What is a headless browser and how does it benefit browser automation?

A headless browser is a web browser without a graphical user interface. It can load and interact with web pages just like a standard browser but runs in the background, making it ideal for tasks such as scraping, testing, and monitoring. Without the need to render visuals, it significantly improves speed and resource efficiency, making it especially useful in CI/CD pipelines or large-scale web applications.

This type of headless automation – commonly referred to as headless browser automation – allows teams to execute large volumes of tests with minimal overhead. For those wondering "what does headless mean in software?", it essentially refers to software that functions without a graphical interface, ideal for scripting and backend tasks.

What is the difference between a headless browser and a normal browser?

A headless browser is a web browser without a graphical user interface. Unlike a normal browser, it operates entirely in the background, which makes it ideal for browser automation, automation testing, and test execution. While both can render HTML, load CSS, and execute JavaScript, the headless browser skips visual rendering, offering faster performance for tasks like performance testing, headless browser testing, and testing web applications through scripts or the command line.

Normal browsers, or full browsers, provide the interactive user interface users rely on for navigation, making them better suited for manual testing and observing real user interactions. Meanwhile, headless browsers are optimized for automated pipelines and resource-constrained environments. However, for visual validation and cross browser testing, using a normal browser is sometimes essential to align with broader goals.

How does headless Chrome support JavaScript execution in automated tasks?

Headless Chrome is a version of the Chrome browser that operates without a UI, allowing developers to run scripts and automate interactions. It fully supports JavaScript execution, making it capable of rendering dynamic content in modern web applications. This is crucial for tasks like scraping sites that rely heavily on JavaScript or simulating user behaviors such as clicks, input, or navigation.

Why is headless testing useful compared to manual testing in web development?

Headless testing allows for automated checks of functionality, layout, and performance without opening a browser window. This speeds up the testing process and integrates easily into development pipelines. In contrast, manual testing is slower, prone to human error, and harder to scale. Headless tests can quickly identify issues after code changes or across different browser versions, ensuring consistent behavior in complex web applications.

For those wondering “what is headless browser” or looking for a quick headless browser meaning – it’s essentially a browser that does everything a regular one does, just without showing the UI. This makes it a go-to for repeatable, scalable headless browser automation. It can also quickly identify issues after code changes or across different browser versions, ensuring consistent behavior in complex web applications.

Can headless browsers be detected?

Headless browsers can sometimes be detected by websites using scripts that check for the absence of a UI, unusual timing in user interactions, or differences in how JavaScript behaves. Some sites may use techniques that detect anomalies in JavaScript execution, mouse movement simulation, or missing browser features compared to standard versions.

However, modern headless browsers like Headless Chrome and Headless Firefox have become more sophisticated, mimicking real user interactions and browser behaviors. Developers can configure code changes and tweak settings to better simulate browser environments and reduce the risk of detection during browser automation or data extraction tasks.

Still, detection remains a challenge in headless testing, and tools may need to be adjusted depending on the testing goals, whether it's stealth scraping, limited testing, or validating a site's response to automated activity. The use of debugging tools and thoughtful test design helps mitigate these detection issues.

Can performance testing be done using headless browsers?

Yes, headless browsers are well-suited for performance testing. They can simulate user flows and track page load times, rendering behavior, and JavaScript execution without the overhead of a UI. This helps developers assess how code changes impact the performance, especially when analyzing rendering delays or optimizing user interface responsiveness.

What is headless browser performance testing, then? It's a method to test site performance in a stripped-down, faster-running environment. For teams with continuous integration goals, headless automation streamlines this process dramatically. If you’re trying to understand what is headless browser, just think of it as a full browser minus the visible window – ideal for fast, scriptable analysis.

About the author

Adelina Kiskyte

Former Senior Content Manager

Adelina Kiskyte is a former Senior Content Manager at Oxylabs. She constantly follows tech news and loves trying out new apps, even the most useless. When Adelina is not glued to her phone, she also enjoys reading self-motivation books and biographies of tech-inspired innovators. Who knows, maybe one day she will create a life-changing app of her own!

All information on Oxylabs Blog is provided on an "as is" basis and for informational purposes only. We make no representation and disclaim all liability with respect to your use of any information contained on Oxylabs Blog or any third-party websites that may be linked therein. Before engaging in scraping activities of any kind you should consult your legal advisors and carefully read the particular website's terms of service or receive a scraping license.