The Top Browser Fingerprinting Techniques Explained

April 1, 2021
Savannah CoplandMarketing Lead

Screenshot of FingerprintJS visitorID data

To generate a highly accurate browser fingerprint, many techniques are used to gather information about the user that can differentiate them from millions of others online. In this article, we review some of the most common methods used in a browser fingerprinting script.

Also known as online fingerprinting, browser fingerprinting is a tracking and identification method websites use to associate individual browsing sessions with one site visitor. Using Javascript, a plethora of data can be collected about a user’s browser and device. When these pieces of information are stitched together, they reveal a unique combination of information that forms every user’s very own ‘digital fingerprint.’ The browser fingerprint is traceable across browsing sessions, even when the user enters incognito browsing or uses a VPN to access a site.

Graphic of browser fingerprinting

Browser fingerprinting can be used to stop fraudsters from attempting to hack, spam, or spoof website owners by accurately identifying site users. Browser fingerprinting is more difficult to circumvent than cookies, as a user’s fingerprint does not change between incognito browsing sessions, or clearing browser data. To generate a browser fingerprint with enough accuracy (or entropy) to uniquely identify a web visitor, the script must use a variety of browser fingerprinting techniques to gather data (called signals) that would vary between visitors. While many visitors to a website may have the same model of iPhone, the software and drivers installed, geolocation, browser and OS version, and even minute variances in the hardware could be different. Each browser fingerprinting technique is able to gather one or more of these signals that aim to identify these small variances between users.

What Information is Gathered?

With browser fingerprinting, a lot of information can be gathered from the browser: the user’s device model, its operating system, its browser version, browser extensions, user timezone, preferred language settings, ad blocker used, screen size and resolution, and all the granular tech specs of his CPU, graphics card, and so on.

Browser fingerprinting technology can capture more than enough specifics about a user’s device and settings to pinpoint them in a sea of internet users. Read our beginner's guide to learn more about how browser fingerprinting works and how each signal adds to a fingerprint's overall accuracy and stability.

FingerprintJS’s browser fingerprinting technology employs several cutting-edge browser identification methods to gather over 100 individual signals. These signals are combined with server-side analysis and deduplication to generate a visitorID, providing a persistent and useful abstraction of a browser fingerprint, which can be volatile if a user changes settings or updates software on their device.

What Are Some of the Different Fingerprinting Techniques?

Canvas Fingerprinting

This browser fingerprinting technique takes advantage of the HTML5 canvas element to identify variances in a user’s GPU, graphics drivers, or graphics card. First, the browser fingerprinting script draws an image, often overlaid with text. Then, the script captures how the user’s browser has rendered the image and text. Every device with different hardware and drivers will render the image slightly differently, distorting its color and shape. A hash is then computed using the rendered image’s data, which serves as the ‘canvas fingerprint.’

Like any other browser fingerprinting technique, the scripts used for canvas fingerprinting operate in the background to keep the user from realizing that the fingerprinting is occurring. This fingerprinting technique is both accurate and not too processing intensive, making it one of the most employed techniques in browser fingerprinting scripts.

To read more about this technique, read our in-depth article on Javascript canvas fingerprinting.

Canvas fingerprint and WebGL fingerprint output from Amiunique.com, showing distorted text and a gradient image.

Canvas and WebGL rendered images, from AmIUnique. Due to how this visitor's specific browser and device rendered these images, they can be narrowed down to a pool of fewer than 0.01% of total visitors.

WebGL Fingerprinting

WebGL fingerprinting is very similar to Canvas fingerprinting as they both use the browser to render text and images off-screen. These images are then used to differentiate users based on their graphics drivers and device hardware.

Media Device Fingerprinting

This technique uncovers a list of all the connected media devices and their respective IDs on a user’s laptop or PC. This includes all internal media components like video cards, audio cards, and all connected or linked devices like headphones.

Media device fingerprinting is not widely used in fingerprinting functions as it requires the user to grant access to their microphone and camera to get a full list of connected devices. As such, this technique is useful for services that innately require webcam or microphone access, such as video chat services.

Audio Fingerprinting

While other fingerprinting techniques force browsers to render a text or image, this technique checks how their devices play sound. Minute differences in sound waves generated by a digital oscillator are impacted by the browser vendor and version used, as well as differences in CPU architecture.

To learn more about audio fingerprinting, read our in-depth tutorial on how audio fingerprinting works using the Web Audio API.

Putting it all together

Multiple fingerprinting techniques need to be used in conjunction with each other to generate a sufficiently accurate fingerprint for user identification. Each technique generates one or more signals, which are then collectively combined into a visitor hash that serves as an individual identifier.

Fingerprinting and Online Fraud Detection

When you’re dealing with fraud, take note that only a small number of your site visitors are responsible for fraudulent activities. Hence, your developer team has to find a way to isolate these site users, identify them, verify them through authentication, and add them to your site blacklist. However, you need to keep these security layers away from your trusted traffic since extra authentication steps can cause an unpleasant user experience. More strict site security can also slow down account accessibility, purchase making, and overall site engagement.

Browser fingerprinting techniques are incredibly useful to identify visitors with a pattern of fraudulent behavior, and then target only these visitors for additional security. Fraudsters often use identity concealing techniques like disabling cookies, surfing through a VPN, or using browsers in incognito mode. These are all areas where fingerprinting proves to be at its best since it identifies users quickly without the reliance on IP addresses and site cookies.

One of the most common fraud use cases is account takeover, where malicious users will try to hack a legitimate user’s account and make purchases or steal their identity. With browser fingerprinting and related user identification technologies, additional security can be added to the login process for suspicious traffic only. This makes it more difficult for untrusted traffic to log in and take over trusted users’ accounts.

If your website is experiencing brute force or bot attacks, a best practice is to ask users to solve a CAPTCHA after each unsuccessful login attempt. After three to five unsuccessful login attempts, set your system to lock out the user for a period of time.

If your users are often the target of phishing scams, you can require email or two-factor authentication when a new fingerprint attempts to log in. And if such fingerprints repeatedly visit your site, you can also blacklist them.

For virtually all types of fraud, the first step in stopping the malicious activity on your website is accurate user identification technology. That way, you can accurately single out the bad apples while keeping your trusted users satisfied with your website performance.

Whether you have a newly-built website or you’ve been in the online industry for years, you can safeguard your leads, clients, and business if you can stop fraud at the source. Start a 30-day trial to see what accurate user identification technology can do for you.