Browser fingerprinting is a user-identification method used by websites for various purposes, such as web personalization, fraud detection, and targeted advertising. It is used for several purposes, including fraud prevention, bot detection, personalization, and cross-site tracking.
What is browser fingerprinting?
Browser fingerprinting, also known as online fingerprinting, is a tracking technique that identifies a browser or device by combining multiple signals exposed during web requests and browser execution, such as IP address, user agent, language, time zone, screen properties, graphics capabilities, and other browser- or device-level characteristics.
What kind of information is gathered?
When you visit a website, your device sends a connection request to the target site to display the website’s content. The target site can access and collect information sent by your browser about your device.
Websites can gather much information about a user’s device with browser fingerprinting technology to tailor recommendations to their visitors. A website, for example, may be able to collect the following information about you without your consent depending on your browser type:
- Web browser (Chrome, Mozilla, Firefox, etc.)
- HTTP header (information regarding your browser and operating system)
- Preferred language
- Timezone
- Screen resolution
- Plugins and extensions
In addition to these common attributes, modern fingerprinting systems may also use rendering and hardware-related signals such as canvas output, WebGL behavior, and audio processing characteristics. Open-source browser fingerprinting tools increasingly reference WebGPU-related properties as an additional source of entropy in some browsers and configurations.
If the website you visit uses fingerprinting technology, it can detect and track your browser. When you return to the same website, it may remember your digital fingerprint and identify you as a returning visitor.
You can find out what is in your browser fingerprint and how unique it is by visiting amiunique.org. As you can see, mine is unique within amiunique.org’s database (Figure 1).
Figure 1: Example of a browser’s fingerprint
By scrolling down on amiunique.org, you can see how many browser and device attributes are exposed during a visit, such as your OS, browser version, language, and time zone.
How does browser fingerprinting work?
With each connection request to a website, you make your device information available to the target website. Assume you use your mobile phone to visit an eCommerce website. Your browser sends a connection request to the target web server when you click on the link to visit the eCommerce website.
Then, the web server will gain access to a small piece of data on your device, such as IP address, browser type, user agent, and much more. In this case, your user agent will inform the web server that you are making a connection request from your mobile phone using Safari. The website will display its content based on the user agent information provided.
The website tracks your behaviors and activities as you navigate the website’s pages to analyze your use of the website. Each time you visit the eCommerce website, your device will be identifiable based on your browser fingerprinting by the website.
What are the different fingerprinting methods?
1. Canvas Fingerprinting
Canvas fingerprinting is a type of browser fingerprinting used to track online users. Canvas fingerprinting forces users’ devices to draw a hidden image to extract a digital fingerprint without their knowledge. This fingerprinting method mostly uses the HTML5 canvas element to reveal information about users’ machines, such as operating systems, browser types, and much more. When a user visits a webpage, the browser renders the image/text content on the page to display the content automatically.
For example, if the website you visit uses canvas fingerprinting technology, the website will instruct your browser to draw an invisible image or text. In doing so, the HTML5 canvas element will reveal information about your machine, such as background color settings, font size/style, graphics card, and other distinctive features (Figure 3).
Since different devices render images and text differently, canvas fingerprinting analyzes how a device renders images and text to assign each user’s device a unique ID.
Figure 3: An example canvas font fingerprinting script
2. WebGL Fingerprinting
WebGL fingerprinting technique, like canvas fingerprinting, is used to expose information about devices’ graphics drivers and screen resolution by forcing browsers to render an image or text. This technique distinguishes users based on their graphics drivers and screen resolution, and creates unique fingerprinting.
3. Audio Fingerprinting
Audio fingerprinting tests how your device plays sound (see Figure 4). Audio fingerprinting works similarly with canvas and WebGL fingerprinting. Since each device produces a unique set of sound waves, audio fingerprinting can identify users based on the audio signals produced by their devices, such as sound hardware and software.
Figure 4: Workflow for browser fingerprinting
Top 3 use cases of browser fingerprinting
Beyond canvas, WebGL, and audio fingerprinting, practitioners are beginning to monitor newer browser-exposed signals, including some WebGPU-related properties, as potential sources of entropy.
These techniques are still evolving, but they show that browser fingerprinting increasingly relies on a wider mix of software, rendering, and hardware signals than older explainers typically describe.
1. Online fraud detection
Websites can detect fraudulent user behavior using browser fingerprinting technology. When a website detects fraudulent user activity, it adds extra authentication steps to the login process to prevent unauthorized access and theft of legitimate users’ accounts.
Commercial device-intelligence vendors began packaging browser fingerprinting into easier-to-use fraud workflows rather than exposing it only as a raw identifier. For example, Fingerprint introduced a no-code Rules Engine to help fraud and risk teams build automated decisions based on device intelligence signals.
2. Tailored content recommendations
It’s possible to delete cookie history and block them on your web browsers. Web browsers such as Google Chrome, Firefox, Safari, and Microsoft Edge enable users to disable cookies. Unlike cookies, browser fingerprints are hard to block. That’s why browser fingerprinting is a more effective technique for advertising to track users’ behaviors and activities across the web.
Websites use fingerprinting to track and analyze visitors’ activities and behaviors to create personalized experiences. For example, when you request a website to display its content, the website can reveal your geo-location by tracking your IP address.
This enables eCommerce sites to recommend locally relevant content and nearby stores to their online visitors. Websites can access the following information about their visitors using browser fingerprint technology:
- User’s current location.
- Type of device the user uses, such as a desktop, tablet, or mobile phone.
- Traffic source, users can reach your website through different ways, such as direct, social media, referral, and paid traffic.
3. Bot detection
Websites use browser fingerprinting to protect themselves from malicious bots. Browser fingerprinting examines the HTTP headers sent by the browser to distinguish web bot traffic from regular browser traffic.
Browser fingerprinting technology analyzes client-side signals to identify web crawlers using bot-detection attributes such as request frequency, unusually high pageviews, and long session durations. It collects the fingerprint of a suspicious browser and compares it with those of regular browsers to detect web bots.
Browser and device intelligence vendors now distinguish between malicious bots, regular human traffic, and authorized AI-agent traffic used for legitimate enterprise automation and agentic commerce. This reflects a shift from simple bot-vs-human detection to more nuanced identity and trust classification.
Is browser fingerprinting legal?
Browser fingerprinting is not automatically lawful or unlawful in every jurisdiction; its legality depends on how the data is collected, the purpose for which it is used, the transparency provided to users, and the legal basis on which the organization relies.
Under European privacy law, fingerprinting-related data may fall within the scope of personal data rules if it can be linked to an identifiable person or used to single out a user or device.
How can you avoid browser fingerprinting?
1. Anonymize your browser
In practice, reducing fingerprintability usually works better through browser-level anti-fingerprinting protections than through generic anonymization alone.
Tor Browser remains one of the strongest mainstream options for reducing uniqueness, and it continued shipping frequent releases in early 2026.
Firefox also documents anti-fingerprinting protections, such as Resist Fingerprinting, which standardize or perturb certain browser outputs to make users look less unique. WebKit has likewise documented newer Safari protections that limit access to some known fingerprinting vectors.
2. Leverage proxies
A proxy server can hide or rotate your IP address, but it does not, by itself, prevent browser fingerprinting because websites can still analyze many non-IP signals exposed by your browser and device.
Likewise, headless browsers are often detectable and should not be described as a reliable anonymity solution on their own. Proxies are best understood as one layer in a broader privacy strategy rather than a complete defense against fingerprinting.
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