Headless browsers 101: Data gathering made simple

In data gathering, headless browsers are an invaluable tool: They allow us to access data on the web quickly and easily. In this article, we're taking a closer look at them.

Headless browsers 101: Data gathering made simple
Sharon Bennett
Sharon Bennett 7 min read
Article content
  1. What is a headless browser?
  2. Use cases for headless browsers
  3. Potential issues with headless browsers
  4. How to choose a headless browser?
  5. Frequently Asked Questions

We mention headless browsers quite often when we talk about data gathering in our articles. This technology has gained a lot of popularity lately as a convenient option not just for web scraping but for testing, too.

So we thought: It will be great to dive deeper into headless browsers and provide you with a detailed overview of them. In this article, we’ll take a look at this tool, figure out how it works, what its use cases are, issues you might face, and the correct approach to such browsers.

What is a headless browser?

There is quite a lot of work behind a page that appears on the screen when we enter a certain website. A browser has to:

  • Send a request to the destination server,
  • Process the answer, and
  • Display it on our device in a way we’ll be able to understand.

For us, it takes a couple of seconds and clicks. Under the hood, however, the browser performs a lot of processes, especially when it comes to displaying the content for us. Here's a crucial difference:

A headless browser does all the work needed to take you to a requested page but without displaying its content. In other words, headless browsers don’t have a graphical user interface — a "head".

When it comes to everything else, it’s just like any other browser you know: It can click buttons, navigate through websites, download and upload content, and so on. You just won’t see a pretty picture of all this activity.

Headless browser accesses the target server

The advantage of headless browsers is that they are more lightweight and way quicker than the usual ones because they lack the user interface. That’s why they’re used for data gathering and testing — to speed up the process without overloading the computer.

Use cases for headless browsers

This tool is quite versatile, and both web developers and data scientists utilize it a lot. Here are some of the situations where a headless browser is an essential tool.

Data gathering

Web scraper collects data from another source

As you already know, headless browsers are widely used for scraping. Running this process through a normal browser would be complete overkill for a computer. Moreover, it’s way faster to go to a web page using a headless browser, gather all the data without the user interface, and go to the next page. Additionally, this tool allows for automating this process — more on that below.

❔ Further reading: How to Protect Your Brand with Web Scraping and Proxies

❔ Further reading: Using Web Scraping to Generate More Leads

❔ Further reading: How to Leverage Web Scraping in Real Estate

Automation of processes

Headless browser performs various routine funtions

A headless browser can automate not only web scraping but other processes too. For example, developers use this instrument to automate scripts, website interactions, and user interface tests. Thus, they can run these processes faster in a browser environment. To ensure the bot's safety (i.e. to avoid getting blocked by the anti-bot systems), they may add a library of headers and fingerprints to their scraper.

Improving performance

Headless browser performs various website checkups

To track system uptime and performance, developers need to run small quick tests to check if the given system component is working correctly. The user interface is not necessary for such tasks, meaning that a headless browser would allow performing these actions quicker as the interface won’t have to load.

Style elements testing

Headless browser performs style elements testing

While a website layout is a user interface itself, you don’t need a GUI to test style elements such as font type and color, page width, and so on. A headless browser that "understands" HTML and CSS is a great tool for quick layout testing. Also, it allows headless testing for JavaScript and AJAX execution, and capturing screenshots of these check-ups.

Other use cases

There are other miscellaneous processes that can benefit from headless browsers. Using them you can:

  • Generate screenshots and PDFs of web pages,
  • Monitor the performance of online apps,
  • Diagnose website performance using a timeline trace,
  • Simulate browsers,
  • Run various tests, and more.

Potential issues with headless browsers

Since this tool allows to automate processes and improve them with the use of different libraries, malefactors use it for fraud. Using headless browsers along with bots they can:

  • Generate fake leads, thus taking down advertisement campaigns and flushing ad budgets of businesses (i.e. ad fraud.)
  • Create fake accounts for various needs — from black hat marketing to phishing.
  • Perform DDoS attacks since headless browsers allow to automate and speed up requests to the destination server.
  • Generate fake web traffic.

We’re sure there are more malicious ways to use this tool. Yet, we’ve mentioned the most widely-spread ones to give you an idea of how malefactors can benefit from headless browser. You need to know this detail if you’re going to gather data using such an instrument. There already are sophisticated tools that help website owners detect and stop headless browsers. Therefore, you might experience difficulties during web scraping.

To avoid issues, use residential proxies that will let your scraper appear as a real user to a destination server. Infatica offers different plans that can satisfy various data gathering needs. Also, we can create a custom plan tailored for your needs. We constantly add new proxies to our pool to provide you with clean and ready-to-use IP addresses — that’s why you can enjoy smooth and fast web scraping with Infatica.

Headless browser connects to the internet via a proxy server

Additionally, you should use libraries of headers that will make the requests a scraper sends appear as those real users would send.

How to choose a headless browser?

Different headless browsers are more suited for different needs. We will list the most popular tools and describe them briefly to let you understand which one to choose considering the type of activity you’re going to perform.

Headless Chromium

Headless Chromium logo

Google provides headless mode for Chrome, turning it into a lightweight and fast headless browser. A headless Chrome browser will be perfect for:

  • Data gathering,
  • PDF file creation,
  • Screenshot creation, and
  • Multi-level navigation testing.

Mozilla Firefox

Headless Firefox logo

Firefox supports headless mode as well. Although you’ll need Selenium, Slimmer JS, or W3C WebDriver to run it in this mode. Headless Firefox can be used for:

  • Testing,
  • Headless automation,
  • Scripting, and
  • Basic unit tests.

Speaking of Selenium, we also have a comprehensive overview of Python web crawlers.


PhantomJS logo

PhantomJS headless WebKit is created to work with the complexities of the internet landscape with the use of command-line testing. This tool is open source and used to be constantly improved by developers, who used it for:

  • Navigation testing,
  • Screenshot creation,
  • User behavior simulation, and
  • Working with different assertions.

Please note that PhantomJS development was suspended in 2018 — although the software itself is still functional, its lack of updates may render it obsolete in the near future.


HTMLUnit logo

This is a Java-based headless browser that’s suited for Java code. HtmlUnit can simulate different browsers to provide developers with the necessary environments. It’s good for testing lots of things such as:

  • Forms,
  • Links,
  • Redirects,
  • Performance of HTTPS pages and HTTP headers, and
  • HTTP authentication.

The bottom line

Headless browsers are versatile and great for data gathering as well as other things. Just don’t forget to add Infatica proxies to the list of your web scraping tools for a smoother and faster process. If you have more questions left about the use of proxies for data gathering, just contact us. We’ll do our best to make things clear for you.

Frequently Asked Questions

Some notable examples of headless browsers include PhantomJS, SlimerJS, and HtmlUnit. They are widely used in headless browser automation and scraping scenarios; also, it's common to use headless browsers for JavaScript application rendering.

Headless Chrome is a way to run the Chrome browser without a graphical interface. This can be useful for things like automated testing, where you want to run tests or scrape websites without dealing with the browser window.

Selenium can be configured to work with headless web browser. This makes it great for automating tests and for scraping data from websites. Headless browsers are also faster and use less memory than traditional web browsers.

When you run tests headless, it means that you're running the tests without a user interface. This is usually done by running the tests in a terminal or command prompt. The most prominent advantage of the headless mode is performance: Your machine doesn't have to spend resources rendering visual components.

Sharon Bennett

Sharon Bennett is a networking professional who analyzes various measures of online censorship. She lends her expertise to Infatica to explore how proxies can help to address this problem.

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