Headless Browser Testing

In your line of work as a software developer, you may have come across the term “headless” such as headless CMS, headless browser, headless linux etc. Generally speaking, in the software world, the word headless denotes the lack of presentation layer (GUI) from the application at hand. Thus, a headless browser is a browser instance which does not have any GUI (graphical user interface) features.

As web applications become increasingly complex, so has the importance of headless browsers. This growing complexity drove the need for new tools that can help with web automation and testing, web scraping, and other server-side browser activities.

What Is a Headless Browser?

A headless browser is defined as a web browser that lacks a graphical user interface. However, just like Chrome and Safari, headless browsers can engage in all the functions a traditional browser can like page navigation, interactions, and executing JavaScript. The only difference is that they do not render the app’s visual aspects, including buttons, images, videos, icons, and more.

When put simply, a headless browser replicates the way bots and crawlers perceive the internet. Rather than loading the visuals and interface that humans use, a headless browser uses a command-line interface or a headless browser API to interact with a website’s code and generate HTML.

How Does Headless Browsing Work?

In the same manner as typical web browsers, headless browsers enable access to numerous online sites. They render the visited websites, perform various actions on the rendered pages, and execute scripts. The difference is that they are not able to render the visual web browser features.

This feature is especially beneficial when it comes to automating processes and performing tests.

Some of the more commonly used tools and browsers are:

  • Chrome’s Headless Browser: Google Chrome can work in a headless manner, boosting its effectiveness and speed.
  • Puppeteer: This is a high level API controlling Chrome or Chromium, made as a Node . js library
  • Selenium: A headless web automation tool compatible with several browsers.

Headless Browsers Use Cases:

Headless browsers serve multiple purposes, such as:

Faster Automation: Actions such as completing online forms, button clicks, or even navigating through different pages can be performed autonomously when required. Moreover, visual elements of web pages are not rendered in a headless browser, so it performs tasks much faster than regular browsers.

Savings on Resources: Due to less consumption of system resources, Headless browsers are ideal to run on servers and in CI/CD pipelines.

Browser Engine: This is the most fundamental part that parses HTML, CSS, and Javascript. Blink (Chrome) , Gecko (Firefox) and WebKit (Safari) are some famous engines.

JavaScript Engine: This runs the Javascript code. Examples include V8 (Chrome) and SpiderMonkey (Firefox).

Network Stack: This manages all network communications which includes HTTP requests, responses and others.

DOM (Document Object Model): This is the programmatic representation of the web page structure.

Rendering Engine: A single component that supports the page layout without producing visual output is processed by the headless browser.

API or Command Interface: The functionality and interaction with headless browsers is achieved through APIs or command-line interfaces compared to GUI interfaces.

Splash is one of the aforementioned headless browsers that is specially engineered for web scraping. It comes with an API HTTP, includes Lua scripts, as well as having an IDE on the browser. Due to its limited HTML emulation support, Splash is not as well known but is rather efficient for a lot of web scraping tasks and works particularly well with Scrapy.

HtmlUnit is a browser which is headless on Java that is intended for use on eccomerce sites. It can work exceedingly well for any project developed on Java. It can simulate clicking, logging into the site, form filling, among other tasks.

JS Phantom is an initial headless web browser developed in Javascript. Unfortunately, it has not been supported for several years.

Pros of Headless Browsers

  • Firstly, a base requirement is the improvement in speeds over normal switches browsers. They load CSS, Java, and other programming code written HTML and other web languages much more quickly as well as not requiring rendering of the HTML.
  • The second reason is the efficiency gained when gathering specific values from a web page. A common example is competitor pricing for product releases.
  • With headless browsers, developers in particular save lots of time, for example, during unit testing when mobile or desktop code changes can be done from the command line.

Cons

  • More speed with browsers is always welcome but it can come at the cost of increased difficulty in debugging.
  • A headless browser’s activities are restricted to backend operations, meaning they cannot be used to resolve front-end problems like producing GUI screenshot outputs.

What is Headless Browser Testing?

For some time, developers have relied on UI driven tests to determine if their programs are functioning correctly. Unfortunately, there are numerous complications with UI driven testing, the largest being stability. Quite often, UI driven tests just do not work when their interactions target the browser. Another challenge is the performance that is so greatly prolonged with these approaches. The solution lies in headless browser testing.

When using headless browser testing, you will run end-to-end tests without the browser loading the application’s user interface, which greatly accelerates everything. Tests now don’t interact with the user interface, which ensures there are no chances of instability. Testing becomes more effective when it is faster and more reliable.

How to Decide on Applying Headless Browser Testing?

If you would prefer faster completion of tests and are not looking for graphical outputs for pre-set tasks, you can opt for using headless browsers. These are scripted, low resource, automated, have a lightweight build and run at an elevated speed. Also, UI tests can be compiled and attached to the build cycle, which is more efficient than manual checking during integration.

The following are the tasks that make partial use of these tools:

  • Automation of HTML responses such as form submissions, mouse clicks, etc.
  • Performing javascript action
  • Scraping content from web pages
  • Monitoring Network
  • Ajax Calls
  • Capture Screenshots of web pages

Top 5 Headless Browser Tester In 2025

1. Playwright

playwright

Playwright is a web testing and browser automation framework. It was created in 2020, and the technology is still highly modern and active. It allows control of Chromium, Firefox and WebKit using a single, consistent API.

With its focus, but not limited to, cross browser web automation, Playwright is evergreen, fast and capable. All these features ensure reliability, as headless browser execution is supported for all browsers on all platforms. For further information, just check specific documentation of Playwright for Python, .NET, or Java.

Advantages:

  • Operates in numerous environments using different languages and browsers.
  • Most extensive functional and API documentation compared to other tools.
  • Modern, efficient, and has millions of downloads each week.
  • Sleek, quick, and powerful.
  • An abundance of additional features such as automatic waits, retries, visual debugging, and configurable reporters.
  • Language consistent and intuitive API.
  • The fastest headless technology available.
  • Maintained and developed by Microsoft.

Disadvantages:

  • Gathers many dependencies.

Additional programming languages supported: Python, Java, and C#.

Supported browsers: Mozilla Firefox, WebKit-based browsers, and chromium based browsers(Edge, Chrome, etc.).

GitHub stars: 60.3K

2. Selenium

selenium

Selenium is one of the most used browser automation frameworks and ecosystem in the IT world. It has so much popularity that there is more than one unofficial port of this library. The Selenium API is standardized and is available in many programming languages.

Selenium is an umbrella project, encompassing a multitude of tools and libraries dedicated to headless browser automation. Particularly, it offers infrastructure for W3C WebDriver specification.

This tool has a complete API for UI testing and scraping. Many complex features tend to be absent such as advanced debugging capabilities and automatic waits.

Advantages:

  • Supports multiple platforms, browsers and languages.
  • This project encompasses more than one library.
  • Several programming languages to choose from.
  • Numerous resources on the internet.

Disadvantages:

  • Does not support auto-wait and other sophisticated parameters.
  • Relatively sluggish when pitted against similar tools.
  • Coding languages that are supported include Java, Python, C#, Ruby, JavaScript as well as a few other unofficially ported languages.

Includes Chromium-based browsers (Chrome, Edge, etc.), Firefox, and WebKit-based browsers (Safari and more).

Number of stars on GitHub is 29,000.

Repositories can be found on GitHub.

3. Puppeteer

puppeteer

Puppeteer is a library for Node.js, offering a higher level interface for controlling Chrome/Chromium via the DevTools Protocol. This library uses a headless browser by default, though it can be switched to full graphical mode. Its superior capability fetches nearly five million downloads every week. Though it originally was connecte4ed only to Chrome, it has grown to include Firefox as well as an experimental function. Further details are explained in our guide for web scraping with Puppeteer.

Advantages:

  • Webpage screenshot taken also converted to PDF
  • Submission forms, UI tests, keyboard input etc. are simulated.
  • Automation of UI Tests for Chrome extensions
  • Fully automated Testing of Chrome Extensions
  • Automation of Chrome Testing

Languages offered: JavaScript

Allows use of: Chrome, and Firefox ( In beta stage )

Stars on GitHub: 86.4 K

Weblink: GitHub

4. Cypress

cypress

Modern web browsers are used with Cypress frameworks, there are many frontend testing tools available on the market, but not each of them provide tested UI with the depth of a full-fledged desktop application, which is the goal of the project. To cover the functionality of a modern web application, developers and QA engineers have the most common pain points while performing tests.

The library is focused on functionality especially on testing, so it is not an all-purpose browser automation libraries. This means it has natively managed use cases such as these outside the limitations of its design. An example of this is managing multiple instances of a browser simultaneously. Instead, it excels at the management of headless browsers designed for testing.

Advantages:

  • Perfect API for E2E testing of modern web applications.
  • Extensive functions such as automatic waiting or network traffic control.
  • End to end, component, integration, and uni tests support.
  • Advanced debugging capabilities with time travel feature.
  • Full integration with the Cypress Cloud platform.
  • Straightforward CI/CD setup.

Disadvantages:

  • Somewhat limited scraping abilities.
  • Not a general automation tool.

Languages: JavaScript

Browsers: Supported on Chrome, Chromium, Edge, Firefox.

GitHub stars: 45.9k

Repository: GitHub

5. Chromedp

cdproto

Chromedp is an all-in-one library to drive headless browsers via the Chrome DevTools Protocol in Go. The package is a high-level DevTools Protocol client that supports web scrapping and unit-testing.

It comes with a complete API to search nodes in a page via plain text, CSS selectors, or XPath expressions. Along with these basic functions, it is also able to simulate touches and mobile device emulation.

Advantages:

  • A full repository powered by examples
  • CSS selectors and XPath expressions are well-supported.
  • Emulates mobile devices and simulates touch interactions.
  • Resources on Linux are highly optimized.
  • Screenshotting is supported.

Disadvantages:

  • Limited E2E testing functions.
  • Support is limited to Chrome only.
  • The speed at which this library is updated is slow compared to other browser automation libraries.

Programming languages supported: Go

Browsers supported: Chrome

GitHub stars: 10.2k

Repository: GitHub

Conclusion

Compared to traditional browsers, headless browsers work much faster because they do not need to load all the components that contribute to the user experience in order to operate. Because of this speed, headless browsers are mostly used for testing web pages. They are used in the testing of automation tasks on a website as well as it’s performance and layout. Data extraction is another common use case for headless browsers. Some of the popular web browsers like Chrome and Mozilla Firefox have headless mode. But headless browsers also have disadvantages and in some situations, testing has to be done in a regular browser.

By wpx_

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