What Is a Headless Browser?
No head = less overhead.
Headless web browsers help developers quickly test apps and websites using automated scripts. But they also have a role in web scraping, and it’s getting more important every year. This article will teach you what a headless browser is, how it allows scraping complex websites, and which headless web browser would work best for your project.
You can also watch this guide in video format:
What Is a Headless Browser?
A headless browser is a web browser without a user interface. Basically, it’s the same Chrome or Firefox we normally use with things we can click or touch stripped away: no tab bar, URL bar, bookmarks, or any other elements for visual interaction.
Instead, such a browser expects you to interact with it programmatically, that is, by writing scripts with instructions for how it should act. Interacting with content this way doesn’t take away from the functionality: you can still emulate clicking, scrolling, downloading, and perform all the same actions you could normally do with a mouse.
Why bother, you may ask. Headless browsers are handy for doing repetitive tasks, such as software testing and web scraping. These are the tasks you’d want to automate anyway. And not having to load unnecessary visual elements saves a great deal of resources.
What Is a Headless Browser Used For?
- Web testing – perhaps the primary use case for a headless browser is testing web-based sites and applications. You can configure it to click on links and various elements, type data into fields, fill in forms, simulate loads, and even go through complete workflows. This helps developers see if the website has any bugs or usability issues they might have missed with manual tests or other tools.
- Web scraping – with JavaScript being so popular, it’s become very hard to scrape some websites with regular HTML extraction tools. Some of the issues include asynchronous loading, endless scrolling, and browser fingerprinting. By fully rendering the website and emulating a real browser, headless browsers allow web scrapers to extract data from even the most challenging targets.
Using Headless Browsers for Headless Testing
Headless testing is a method of running automated tests on a web application using a browser that operates without a graphical user interface (GUI).
In this mode, the browser performs all the operations it would in a visible session, such as loading pages, rendering JavaScript, interacting with elements (forms, buttons), without actually showing the interface on the screen. Headless testing is useful for developers since it’s faster and more resource-friendly compared to testing with a full browser window.
This testing method helps verify whether web applications function correctly across different browsers, ensures bots (i.e., web crawlers or scrapers) can navigate the site correctly, and checks whether the application runs smoothly without loss of functionality.
How Headless Browsers Help in Web Scraping
When it comes to web scraping, headless browsers are either irrelevant or vital to a project’s success. It all depends on the website you’re after.
If that website doesn’t rely on JavaScript elements to display content, or if it doesn’t use JS-based tracking methods to block web scrapers, you won’t need a headless browser. In such cases, regular web scraping apps or libraries like Requests and Beautiful Soup will do the job faster and with less complexity.
However, if you’re dealing with dynamic AJAX pages, or data nested in JavaScript elements, a headless browser will be your best bet to extract the information you want. That’s because you’ll need to render the full page like a real user, and regular HTML scrapers don’t include such functionality.
Another important use for a headless browser is to overcome browser fingerprinting. It’s a whole new can of worms that involves parameters like screen resolution, timezone, IP address, JavaScript configuration, and more. Sophisticated websites use fingerprinting to track their users and block web scraping bots. With a headless browser, your scraper can emulate the fingerprint of a real device.
Pros and Cons of Web Scraping with Headless Browsers
Headless browsers offer many advantages for web scraping projects by simulating a real user’s interaction with websites. This allows scrapers to navigate JavaScript-heavy websites where traditional HTTP-based (not dynamic) approaches might not suffice.
Tools like Selenium or Playwright allow the web scraper to load and handle dynamic content, click buttons, scroll, type, or interact with forms, making them vital for scraping sites that rely on JavaScript-rendered elements. Also, since they can mimic real user behavior, anti-bot protection systems are less likely to detect your scraper.
However, headless browsers also come with some drawbacks. While these tools can avoid bot-detection systems by mimicking human behavior, there’s no guarantee they’ll remain undetected. Powerful protection services like Cloudflare can still notice automated activity. You’ll have to pair a headless browser with rotating proxies to make requests more natural.
Additionally, headless browsers are typically more resource-intensive than other scraping methods. This means that you’ll need more memory and processing power, which can slow down performance and increase costs, especially for large projects.
Choosing the Best Headless Browser Library for the Task
If you’ve decided to try out a headless browser for web scraping, there are multiple options you can choose from. Here are some of the main ones:
Run Any Headless Browser in Selenium
Selenium is an open-source automation tool. Its primary purpose is to perform automated tests, but Selenium can also be used for web scraping. The tool allows writing scripts for all the main web browsers – Chrome, Firefox, Opera, Edge, and Safari – in multiple programming languages, including Python, Java, Ruby, and C#. Selenium isn’t very fast, and it’s not designed for scraping the web, but it’s nevertheless a popular tool for controlling headless browsers.
Try a New Multi-Engine Headless API – Playwright
Playwright is a relatively new node.js library for controlling headless browsers. It’s maintained by Microsoft. Like Selenium, Playwright supports page navigation, input events, downloading and uploading data, emulating mobile devices, and more. The library’s biggest advantage is that it can emulate all three major browser groups: Chromium, Firefox, and WebKit.
Control Headless Chrome with Puppeteer
Puppeteer is a node.js library for controlling headless Chrome (and as of recently, Firefox). It’s built by Chrome’s developers, so the library is well maintained and has good compatibility with its ‘puppet’ browser. Puppeteer allows crawling pages, clicking on elements, downloading data, using proxies, and more. It’s become one of the most popular options for controlling a headless browser in web scraping.
Puppeteer also has a sister library for Python called Pyppeteer. However, it’s unofficial, so you might not get the same features or support.
Frequently Asked Questions About Headless Browsers
Headless mode means that the software in question runs without a graphical user interface.
Yes. Some of the libraries that use Python to control a headless browser are Selenium and Pyppeteer.
Yes. The functionality was implemented in the first part of 2020.
