What Is Browser Fingerprinting? How Sites Recognise You Without Cookies
Browser fingerprinting identifies a browser by the combination of details it reveals: its graphics output, installed fonts, screen size, timezone, language, hardware and dozens of smaller signals. No single value is unique, but together they usually are, and unlike cookies the fingerprint survives clearing storage and changing IP address. A proxy changes where you connect from; it does nothing to your fingerprint. That is why multi-account setups pair every proxy with a separate browser profile.
- fingerprinting
- anti-detect browser
- privacy
- detection
Table of contents
What goes into a fingerprint
| Signal | What it reveals | Why it is distinctive |
|---|---|---|
| Canvas | How your GPU and drivers render text and shapes | Tiny rendering differences between machines |
| WebGL | Graphics card vendor and renderer | Narrows the hardware sharply |
| Audio context | How the audio stack processes a signal | Varies by hardware and OS |
| Fonts | Which fonts are installed | Software and language packs differ |
| Screen | Resolution, colour depth, pixel ratio | Monitor setups vary widely |
| Navigator | User agent, platform, CPU cores, memory | Hardware and version combination |
| Locale | Timezone, languages, number formats | Should match your IP's country |
| TLS and HTTP/2 | How the connection is negotiated | Distinguishes real browsers from scripts — see TLS fingerprinting |
Fingerprinting vs cookies
Cookies are stored by the site on your device, and you can delete them. A fingerprint is computed from your device each time, so there is nothing to delete. That is why it is used for fraud prevention and bot detection: it recognises a returning browser that has cleared its storage, switched to incognito or moved to a new IP.
Consistency matters more than uniqueness
Most people assume the goal is a rare fingerprint. In detection, the bigger signal is inconsistency: values that cannot belong together. A few examples that anti-bot systems check for:
- A Windows user agent with a macOS font list.
- A German IP with a US timezone and English-only languages.
- An iPhone user agent reporting eight CPU cores and a desktop GPU.
navigator.webdriverset to true, or automation flags in the browser.- JavaScript overrides that do not look native when inspected.
A common, internally consistent fingerprint blends into the crowd. A rare one with a contradiction in it stands out immediately. Spoofing badly is worse than not spoofing.
Where the proxy fits
The proxy supplies the network half of the identity: the IP, its country, its ASN and its reputation. The fingerprint is the device half. Sites check both and compare them. That is why the standard setup for multiple accounts is one anti-detect browser profile per account, each with its own dedicated proxy, and the profile's timezone and language set from the proxy's location.
The network half of every profile
Dedicated ISP proxies from €1.80/IP — one static, clean address per browser profile, in 20+ countries.
Can you avoid browser fingerprinting?
- For privacy: browsers with built-in fingerprinting protection make many users look alike, which is more effective than randomising everything.
- For multiple identities: an anti-detect browser gives each profile a separate, consistent fingerprint.
- For automation: a real browser engine with a realistic profile beats a bare HTTP client, whose TLS signature gives it away before any JavaScript runs.
You can see what your own browser reveals on the EFF's Cover Your Tracks test, and what a site sees of your connection with our user agent tool and IP checker.
Sources
Frequently asked questions
What is browser fingerprinting?
It is a technique that identifies a browser by combining many details it reveals, such as graphics rendering, fonts, screen size, timezone, language and hardware. Together these values are usually unique enough to recognise the same browser again.
Does a proxy or VPN stop browser fingerprinting?
No. A proxy or VPN changes your IP address, but the fingerprint is computed from your browser and device. You need a separate browser profile to change it.
Does incognito mode prevent fingerprinting?
No. Incognito mode stops cookies and history from being saved, but the browser reveals the same hardware and configuration details, so the fingerprint stays largely the same.
What is canvas fingerprinting?
A site draws hidden text or shapes on an HTML canvas and reads back the pixels. Small differences in GPU, drivers and fonts make the result distinctive for each machine.
How do anti-detect browsers handle fingerprinting?
They give each profile its own consistent set of fingerprint values, so several accounts on one computer look like separate devices. Each profile should also have its own proxy with a matching location.
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