Browser Fingerprint Test — What Sites Know About You (2026)
Every time you load a webpage, your browser silently leaks hundreds of data points — your GPU model, installed fonts, audio processing characteristics, screen metrics, and more. Websites combine these signals into a unique fingerprint that identifies you across the web, even in incognito mode, even with a VPN, even after clearing cookies. This guide explains exactly how it works — and how to test yours right now.
What Is Browser Fingerprinting?
Browser fingerprinting is a tracking technique that creates a unique identifier for your browser by combining dozens of properties that are specific to your device, operating system, and browser configuration. Unlike cookies, it requires no storage — it is reconstructed on demand by any website.
Research by the Electronic Frontier Foundation shows that browser fingerprints are highly unique: only about 1 in 286,777 browsers share the same fingerprint. That means even in a crowd of millions, your browser is almost certainly uniquely identifiable.
The 32 Fingerprinting Signals UNDETECT.CLUB Detects
How Browser Fingerprinting Works — Technical Deep Dive
Canvas Fingerprinting
Every browser draws text and shapes using the operating system's font rendering engine and the GPU's
graphics pipeline. Even the same font at the same size renders with sub-pixel differences depending on
your GPU model, driver version, OS anti-aliasing settings, and screen DPI. A website draws a hidden
<canvas> element with a specific text string and reads back the pixel data as a
data URL. That hash is your canvas fingerprint — stable across sessions and invisible to you.
WebGL Fingerprinting
The WebGL API exposes your GPU vendor and renderer string via
WEBGL_debug_renderer_info. This gives sites your exact GPU model (e.g., "NVIDIA GeForce RTX 4090 / PCIe / SSE2").
Combined with shader precision formats, viewport limits, and extension support, WebGL creates a
highly unique hardware fingerprint.
Audio Fingerprinting
The Web Audio API processes sound differently on each combination of OS, browser, and hardware.
Using an OfflineAudioContext with a DynamicsCompressor node, sites
generate a silent audio buffer and hash the output. The floating-point values differ by tiny
fractions across devices — imperceptible to humans but unique as a fingerprint.
Font Enumeration
Browsers don't expose your installed fonts directly, but JavaScript can detect them by measuring
how text is rendered with canvas.measureText(). If a font is installed, text renders
at a different width than the fallback font. Testing hundreds of font names in a loop reveals
exactly which fonts you have installed — a uniqueness signal with thousands of possible combinations.
Understanding Your Fingerprint Score
When you run a scan at UNDETECT.CLUB, you get a Uniqueness Score from 0 to 100:
Red Flags to Watch For in Your Scan
| Signal | What It Means | Risk |
|---|---|---|
| WebRTC Local IP exposed | Your real private IP is visible to websites | HIGH |
| navigator.webdriver = true | Browser is controlled by automation | HIGH |
| SwiftShader / Mesa GPU | Virtual machine or headless browser detected | MEDIUM |
| Timezone mismatch | Browser TZ doesn't match IP geolocation TZ | MEDIUM |
| UA/Platform inconsistency | Spoofed user agent detected | MEDIUM |
| 0 fonts detected | Fingerprint spoofing tool active | LOW |
| Canvas noise detected | Brave or extension adding noise — good! | GOOD |
How to Reduce Your Browser Fingerprint
Use a Privacy Browser
- Brave Browser — adds random noise to canvas, WebGL, and audio fingerprints. Built-in, no setup needed.
- Firefox + privacy.resistFingerprinting — makes all Firefox users look identical. Set via
about:config. - Tor Browser — strongest protection, standardizes all fingerprint signals. Slowest option.
Browser Extensions
- uBlock Origin — blocks fingerprint scripts at the network level
- Canvas Blocker — randomizes canvas output per-site
- JShelter — comprehensive JS API restriction extension
Reduce Font Uniqueness
Don't install unusual fonts. The more fonts you have, the more unique your fingerprint. Stick to the default OS font set.
Fix the AI-Generated Prompt
UNDETECT.CLUB includes an AI prompt block that appears after your scan if issues are found. It lists every detected problem with technical values and generates a ready-to-paste prompt for ChatGPT, Claude, or Gemini — so you can get step-by-step fix instructions without researching each issue yourself.
Frequently Asked Questions
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