# What Is Browser Fingerprinting? How It Works and Its Limits

By Steven Van · 2026-10-12

Browser Use explains the signals sites collect, how reliable matching is, and why fingerprinting can get AI agents and scrapers blocked.

Browser Use has published an explainer on browser fingerprinting, covering how websites identify browsers, which signals they collect and where the technique falls short. The article is aimed at people whose [Browser Use](<https://creatorstoolbox.com/resources/browser-use>) agents or scrapers keep getting blocked.

## How fingerprints are built

Websites collect browser characteristics such as the user agent string, language, screen dimensions, available fonts and canvas rendering. These are combined into one data structure and hashed, and the resulting value can be compared across visits. The article says this can help a site recognise a returning browser after its cookies have been deleted.

## Signals covered

- **Passive fingerprinting:** uses what requests and connections already expose, including HTTP headers, the IP address and TLS handshake characteristics, without running code in the browser.

- **Active fingerprinting:** runs JavaScript to read screen dimensions, measure text, or render graphics and process audio.

- **Specific techniques:** canvas, WebGL, font and audio fingerprinting (the audio method uses an OfflineAudioContext and does not record the microphone).

## Uses and limits

The article lists tracking and analytics, fraud prevention and bot detection as the main uses. For bot detection, it notes that a flag such as navigator.webdriver can report that a browser is automated, so a site can challenge AI agents and scripted scrapers without knowing what controls the browser. Changing the model or prompt does not change the browser characteristics that triggered the check. Network reputation, request patterns and session state also matter when diagnosing blocked requests.

On limitations, the article says different browsers can share a fingerprint, and that browser updates can change the result. It compares fingerprints with tracking cookies and IP addresses, and notes that each method has its own weak points.

Browser Use says it has been focusing on stealth browsers, and that its hosted browser infrastructure handles the browser environment separately from the agent's reasoning. The full text is in the [original article](<https://browser-use.com/posts/what-is-browser-fingerprinting>).

[![](<https://browser-use.com/images/what-is-browser-fingerprinting/fingerprint-city-v4-7029b24e1b.webp>)](<https://browser-use.com/posts/what-is-browser-fingerprinting>)

![Browser Use](<https://www.google.com/s2/favicons?domain=browser-use.com&sz=128>)

Browser Use

Open-source browser automation platform for AI agents — let LLMs drive a real browser to research, fill forms, scrape, and complete multi-step tasks.

[View Browser Use →](<https://creatorstoolbox.com/resources/browser-use>)

Sources

[Original source](<https://browser-use.com/posts/what-is-browser-fingerprinting>)

[Read What Is Browser Fingerprinting? How It Works and Its Limits on Creators Toolbox](<https://creatorstoolbox.com/blog/browser-use-what-is-browser-fingerprinting-how-it-works-and-its-limits>)

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Canonical source: https://creatorstoolbox.com/blog/browser-use-what-is-browser-fingerprinting-how-it-works-and-its-limits