Are you new to the headless browser technology? Then this page has been written for you. This article is an ultimate guide to headless browsers. You are going to learn what it is, its uses, dark sides, and much more.
What is a Headless Browser?
A headless browser is a web browser without a Graphical User Interface (GUI). To put it better, any browser that has the capabilities of a full-fledged web browser but does not have a User Interface and can only be operated using a script or any other software is known as a headless browser.
As stated earlier, the Chrome browser can run in headless mode, and in fact, when discussing headless browsers, headless Chrome is the most popular one available. Some of the popular headless browsers include headless Firefox, PhantomJS, SimpleBrowser, Splash, HtmlUnit, and TrifleJS.
One thing you need to know about these browsers is that they are controlled using command lines and scripts in supported programming languages. The content of the pages they access is also accessible via the command line. For headless browsers to work, they will need a controller or driver with the likes of Selenium, Puppeteer, and Cypress as the popular options.
Headless Browsers Use Cases
Headless browsers have many use cases that can be summed up into one word – automation. Yes, headless browsers are used for accessing websites in an automated manner – and what you do with that is up to you. Let take a look at some of the few activities you can use headless browsers for.
Modern Website and Application Testing
In the past, web pages are static pages, and testing them using does not present any major challenge using traditional HTTP libraries. However, in recent times, things have changed rapidly, and some modern websites have the feel, look, and User Interface of native applications.
Web Data Extraction
Are you looking for a means to screenshot web pages and save the screenshots in picture formats? With a headless browser, you can get a page to load and render completely and then screenshot the screen.
Why Use a Headless Browser?
It might interest you to know that regular browsers can be automated to carry out all of the tasks that a headless browser will. Why then will you want to make use of a headless browser instead of a regular browser with a GUI?
It might interest you to know that even at the time of developing an application that utilizes a headless browser, you will need to make use of a browser with GUI for testing and debugging. But the moment the development of the application is complete, you ditch the GUI.
It turns out that headless browsers are faster than regular browsers because of the fact that no GUI is created, and as such, less memory, time, and resources are consumed. It is also important you know that headless browsers are the only browsers you can use on machines and platform that is accessible only via the command line as in the case of some Linux distribution and servers.
Top Headless Browsers for Automation
We have been mentioning headless browsers; it is time to describe some of the best headless browsers. We will be looking at 3 of them below.
When the term headless Chrome is mentioned, it does not mean that it is a separate browser from Chrome – it is a mode in the regular Chrome web browsers, you know. The headless mode in Chrome brings all the modern web features of Chromium and the Blink rendering engine to the command line.
The headless mode is supported by the latest versions of Chrome and first appeared in version 59. Headless mode is supported on Linux, macOS, and Windows. It is supported by most browser automation tools, including Selenium and Puppeteer.
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Headless Firefox is just like a mode in Firefox, just like in Chrome. It has been supported on Linux since version 55. Headless mode support for Windows and Linux gets added in version 56.
Selenium is one of the best web browser controller for headless Firefox. With headless Firefox, you have access to all the Firefox features except for the GUI – but with the reduction in memory and resource usage.
Aside from mainstream browsers such as Chrome and Firefox, PhantomJS is one of the most popular headless browsers. Unlike the other two mentioned above available via headless mode support, PhantomJS is only available as a headless browser. PhantomJS has been around since 2010 and has been used a lot.
Headless Browsers and Anti-Bot Systems
Make no mistake about it, except you are using a headless browser on sites you have control over; you will most likely get interrupted and blocked by anti-bot systems of sites. This is because headless browsers are known for automated access only – and not all web services allow automated access.
Even Google that makes use of headless Chrome for crawling Ajax pages would not allow you to use the same headless Chrome to access Google services except via their official APIs.
For this reason, you will need to incorporate anti-bot bypassing techniques if you are dealing with sites with anti-bot systems in place. Interestingly, unlike other tools, evading anti-bot systems using headless browsers is easy and stress-free.
This is because it is a regular browser, and as such, the major indices that will give it out will be IP address and Captcha.
Interesting, there is an easy walkaround method to bypass these – Crawlera or any other proxy API to the rescue.
Headless Browsers + Crawlera: A Match Made in Heaven for Web Scraping
As stated earlier, anti-bot systems of websites will block traffic originating from a bot. Considering the fact that most scripts that make use of headless browsers are either bots or have bot features, it is wise to expect blocks and then plan on how to circumvent them.
With the use of proxy servers, you can take care of the IP based restrictions while Captcha solvers will help you deal with Captcha. However, going this route will be a lot of work. You can just make use of Crawlera to get it done.
Crawlera is a proxy API developed by Scrapinghub for web scraping. Under the hood, Crawlera is a proxy service – but unlike regular proxies, Crawlera has been designed to help you evade anti-bot systems.
In fact, with this service, you do not have to worry about proxy management, IP rotation, throttling, and all of that. Just send a request and get back the response – it is as simple as that as a result of Crawlera's in-house system of bypassing anti-bot systems. It does not only mask your real IP address and rotate the IP address it assigns to your requests but also takes care of Captchas.
One thing you will come to like about Crawlera is that pricing is based on successful requests, and as such, you only pay for successful requests. With Crawlera, you can enjoy 10K free trials for a limited time. Crawlera is not the only proxy API or scraping API in the market; there are many others, including ScrapingAPI and ScrapingBee. You can make use of the proxy APIs mentioned together with a headless browser and scrape Ajaxified websites.
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Are Headless Browsers Illegal?
I have seen many newbies asking if the use of headless browsers is illegal – in fact, it is even one of the listed questions on the Google result page for the headless browser keyword. The short answer to the question is NO. headless browsers are not illegal – they are just a tool for automating web actions.
It is what you do with it that makes it illegal or not. Take, for instance, web scraping on a general base is considered legal provided the data being scraped is publicly available, not copyrighted, and does not require a login to access.
On the other hand, ticket scalping, Distributed Denial of Service (DDoS) attacks, ad fraud, and other forms of malicious activities that can be done using headless browsers are illegal.
So, headless browsers are not illegal – it is what you use them for that could put you in legal trouble. It is important you know that this is not a piece of legal advice, and it will be better if you seek such from a legal practitioner.
The features it brings to the command line has opened up a lot of opportunities not only to web developers that use it for automated web testing but also bot developers. Aside from headless browsers, there are some other tools that can be used in place of headless browsers, such as simulated browser environments like Zombie.js and ENVJS.