What Is Browser Fingerprinting? How You're Tracked Without Cookies
You've cleared your cookies. You've enabled private browsing. You might even be running a VPN. But none of that matters to browser fingerprinting — a tracking technique that identifies you using your device's hardware and software characteristics, no stored data required.
This isn't theoretical. Major advertising networks, fraud detection systems, and analytics platforms use fingerprinting as a primary or supplementary identification method. The AmIUnique research project has collected over 2.86 million fingerprint samples, and in February 2025, Google reversed its 2019 position and began allowing digital fingerprinting for ad tracking — a practice it had previously called "wrong."
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Our fingerprint analyzer checks canvas, WebGL, audio, fonts, and more — all client-side, nothing sent to any server.
Run Fingerprint Test →How Browser Fingerprinting Works
Every browser and device combination renders graphics, processes audio, and handles fonts in slightly different ways. These differences are invisible to you but detectable through JavaScript APIs that any website can access. Individually, each data point isn't very identifying. Combined, they create a fingerprint that is nearly unique.
The Major Fingerprinting Vectors
Canvas Fingerprinting — A website draws an invisible image using the HTML5 Canvas API, then reads back the rendered pixels. The exact same drawing code produces slightly different pixel data on different hardware due to GPU differences, driver versions, anti-aliasing algorithms, and OS-level font rendering. The pixel data is hashed into a unique identifier. Research shows canvas fingerprinting alone can uniquely identify over 60% of users.
WebGL Fingerprinting — Similar to canvas but uses the WebGL 3D graphics API. It renders a 3D scene and collects GPU-specific data: the renderer string (e.g., "NVIDIA GeForce RTX 4070"), vendor, supported extensions, shader precision, and maximum texture sizes. Even identical GPUs with different driver versions produce different outputs. WebGL is harder to spoof than canvas because it involves hardware-level data.
Audio Context Fingerprinting — Processes an audio signal through the AudioContext API and measures the output. Different hardware and software stacks produce measurably different audio processing results, even between devices with identical specifications. Firefox's Strict mode standardizes audio output to approximately 35.75 for all users, making them indistinguishable on this vector.
Font Fingerprinting — Detects which fonts are installed by measuring how text renders at specific sizes. The set of installed fonts varies significantly between systems and is a high-entropy identifier — meaning it contributes significantly to uniqueness.
Hardware & System Fingerprinting — Screen resolution, color depth, device pixel ratio, number of CPU cores (via navigator.hardwareConcurrency), available memory, timezone, language settings, and platform string all contribute to the fingerprint. Battery status was once available but has been removed from most browsers due to privacy concerns.
Why Common Privacy Measures Don't Work
Clearing Cookies Does Nothing
Browser fingerprinting was specifically developed as a cookieless tracking method. Because it reads your hardware and browser properties in real time, there is no stored data to clear. Deleting cookies, cache, or browsing history has zero effect on your fingerprint.
VPNs Don't Change Your Fingerprint
A VPN changes your IP address and encrypts your traffic — both valuable for privacy. But your canvas rendering, WebGL output, installed fonts, screen resolution, and every other fingerprint vector remain identical whether you use a VPN or not. Our fingerprint test will produce the same result with or without a VPN.
Incognito Mode Doesn't Help
Private browsing prevents cookies and history from being saved locally, but your browser still sends all the same fingerprint data to every website you visit. Your canvas renders identically, your fonts are the same, and your hardware hasn't changed.
Which Browsers Actually Resist Fingerprinting?
A December 2025 study by Brightside AI tested commercial fingerprinting systems (not academic tools) against major browsers and found significant differences in protection.
Firefox (Enhanced Tracking Protection: Strict) takes a compound approach: it generalizes hardware information (reporting "Apple M1, or similar" instead of the exact chip), standardizes audio output so all Firefox Strict users produce the same value, and adds session-based randomization to canvas. This puts users into a large anonymity set.
Safari similarly generalizes, reporting "Apple GPU" instead of specific chip models. Combined with Intelligent Tracking Prevention, this makes Safari users harder to distinguish from each other.
Brave uses randomization ("farbling") — adding small random noise to fingerprint outputs. However, the 2025 "Breaking the Shield" research paper demonstrated that this randomization can be defeated through statistical analysis. The researchers attacked Brave's farbling mechanism and nine fingerprint-defending extensions, concluding that randomization-based defenses are particularly vulnerable.
Tor Browser provides the strongest protection by making all users look identical: canvas reads are blocked or standardized, WebGL is disabled, fonts are limited to a standard set, and timing sources are rate-limited. The tradeoff is significantly reduced speed and some website compatibility issues.
What Can You Actually Do?
Start by understanding your current exposure. Run our browser fingerprint test to see how unique you are and which specific vectors are most identifying.
Then consider these practical steps: use Firefox with Enhanced Tracking Protection set to Strict, install uBlock Origin (which blocks many fingerprinting scripts), resist the urge to install many browser extensions (each one makes you more unique), and if you need strong anonymity for specific tasks, use Tor Browser. For everyday browsing, Firefox or Safari provide the best balance of protection and usability.
Also check what other information your browser reveals: the HTTP header analyzer shows every header your browser sends to websites, and the WebRTC leak test checks if your IP is exposed through browser APIs.
Frequently Asked Questions
What is browser fingerprinting?
Browser fingerprinting is a tracking technique that identifies your device by collecting dozens of data points about your browser and hardware — including canvas rendering, WebGL graphics, installed fonts, screen resolution, timezone, and audio processing. These combined attributes create a nearly unique identifier, even without cookies.
Can a VPN prevent browser fingerprinting?
No. A VPN only changes your IP address. Browser fingerprinting relies on your device's hardware and software characteristics, which a VPN cannot alter. Canvas rendering, WebGL output, fonts, and other fingerprint vectors remain identical whether you use a VPN or not.
Does clearing cookies stop fingerprint tracking?
No. Browser fingerprinting specifically exists as a cookieless tracking method. Because it relies on your hardware and browser configuration rather than stored data, clearing cookies, cache, or browsing history has zero effect on your fingerprint.
Which browser is best for preventing fingerprinting?
Firefox with Enhanced Tracking Protection set to Strict and Safari provide the strongest practical defenses by generalizing hardware data. Tor Browser offers the most protection but at the cost of speed. Brave's randomization approach was defeated by statistical analysis in a 2025 study.
How unique is my browser fingerprint?
Most browser fingerprints are unique among millions of samples. Canvas fingerprinting alone can uniquely identify over 60% of users. Run our free fingerprint test to check your own uniqueness score.