Browser Fingerprinting

WEB BROWSER FINGERPRINTING

Anyone concerned with being tracked on-line needs to be familiar with web browser fingerprinting. What is it? Think death by a thousand cuts. Fingerprinting combines a thousand small trivial pieces of information about your browser, you hardware and your operating system to form a unique picture of you. Think of each piece of information as a brush stroke in the unique painting made of your browser.

Some attributes that are examined are: the computer operating system, the time zone you are in, the language your computer is using, how much RAM memory the computer has, the screen height and width in pixels, the height/width of the browser window, the version of the browser you are using, the fonts that are installed, the plug-ins that are installed, the supported audio and video formats, your public IP address and much more. You can get a better feel for this at some of the "tester" websites below.

TESTING

One website for testing the fingerprinting of a web browser is amiunique.org. As of Nov. 15, 2019 they had collected 1,408,000 fingerprints. By March 12, 2020 it was up to 1,713,000.
The EFF has offered an online test similar to amiunique.org since 2010. It used to be called Panopticlick but now it is called Cover Your Tracks. In August 2021, I tried this on Windows. Brave with OpenDNS and no plug-ins did well: "your browser has a randomized fingerprint". Firefox using NextDNS and with uBlock Origin and Privacy Badger installed, failed, it had a unique fingerprint.
fingerprint.com is a demo for a user tracking service. Viewing it once is boring. But coming back later and seeing "This is visit number 3 using Chrome" is spooky. No information is provided as to what data goes into forming the fingerprint.
fingerprintjs.com/demo is a demo of how good fingerprinting can be from a company offering it as a service. As of Feb. 2025, it now at fingerprint.com/demo/
The deviceinfo.me website shows many of the computer attributes used in fingerprinting.
Web browser fingerprinting - testing the testers by me Nov. 2019. How well do the above two tester websites work? Not as well as they could.

DEFENSE

Two techniques that I know of are: blocking scripts that are known to create fingerprints and lying to JavaScript (only the browser can do this) when it asks for certain pieces of information that are known to be used in fingerprinting.

What gets tracked/fingerprinted is a web browser. So, use more than one, which is a good idea for other reasons too.
Safari: Apple is Turning on a Powerful Safari Anti-Tracking Tool for Everyone by Radu Tyrsina for Mac Observer. September 26, 2025. In iOS 26 and macOS Tahoe 26, advanced fingerprinting protection is enabled by default in every tab, not just in Private Browsing. To see this
iOS: Settings -> Safari -> Advanced -> Advanced Tracking & Fingerprinting Protection -> the best option is "All Browsing"
macOS: open Safari -> Settings -> Advanced -> set "Use advanced tracking and fingerprinting protection" to "In all browsing"
ChromeOS: An excellent defense against fingerprinting is a Chromebook in Guest Mode. All Chromebooks of the same model running the same version of ChromeOS should share a fingerprint. Interesting fact: only 0.23% of the devices tested by amiunique.org were Chromebooks.
Tor Browser: The Tor browser has a number of anti-fingerprinting features enabled by default. It runs on Windows, macOS, Android and Linux. Note however that websites will be very slow to load.
Mullvad browser: Even when connected to a VPN, a web browser can still spy on you. In April 2023, Mullvad released a new web browser, the Mullvad Browser. Basically, this is the Tor browser but without Tor. The Mullvad Browser can be used with any OS level VPN or even without a VPN at all. Both the Tor and Mullvad browsers have many customizations that avoid fingerprinting, that is, they try to make all users of the software appear to be the same. The Mullvad browser is free and available for Windows, macOS and Linux. There is no Mobile version. It uses the Mullvad DoH DNS service that is available to everyone, not just Mullvad customers. They offer two free DNS services, the default one does not block ads, but this can be changed.
LibreWolf: From their website: "LibreWolf is designed to increase protection against tracking and fingerprinting techniques, while also including a few security improvements. This is achieved through our privacy and security oriented settings and patches. LibreWolf also aims to remove all the telemetry, data collection and annoyances ... " It runs on Windows, macOS and Linux.
Firefox: Firefox introduced fingerprint protection back in January 2020 with version 72. See Firefox 72 blocks third-party fingerprinting resources by Steven Englehardt of Mozilla. Their methodology at the time was to block third-party requests from companies known to engage in fingerprinting. By November 2024, the browser has options for both Known Fingerprinters Protection and Suspected Fingerprinters Protection. See Firefox's protection against fingerprinting from Mozilla. This is configured at Settings -> Privacy & Security. Known Fingerprinters Protection is enabled when Enhanced Tracking Protection is set to Strict. To see if Firefox blocked anything on the current page, click on the shield to the left of the address bar. If there is right pointing arrow on the Fingerprinters line, then it blocked something (last checked with Firefox v133 on Windows Jan. 2025). To see what it blocked, click on the word Fingerprinters.
Psylo (iOS only): see Psylo browser tries to obscure digital fingerprints by giving every tab its own IP address by Thomas Claburn for The Register June 24, 2025.
Brave: Brave has two generations of defense. In March 2020 Brave announced their second defensive approach - randomizing fingerprintable values in ways that are imperceptible to humans, but which confuse fingerprints. Quoting: "This approach is fundamentally different from existing fingerprinting defense approaches ... [that] attempt to make all browsers look identical to websites (an impossible goal). Brave's new approach aims to make every browser look completely unique, both between websites and between browsing sessions." They claim this provides the strongest fingerprinting protections of any popular browser.
See Fingerprinting defenses 2.0 by the Brave Privacy Team. May 18, 2020
Their older defense was the Device Recognition option in the Settings. I found that it worked, here you can see it reporting that it blocked two fingerprint attempts by Ars Technica.
Disconnect offers a free browser extension that blocks trackers. Maybe it also blocks fingerprinting. They partnered with Mozilla in providing the Firefox defense.
OS Defense: The Tails operating system might be a defense. It is a version of Linux that runs off a boot CD/DVD/USB flash drive and always uses the Tor network and the Tor browser. Everyone using the same version of Tails will have much in common. However, attributes of the screen will differ. Also, it is a big pain to setup. And, again, the Tor network alone, is no defense.
The GoLogin browser confuses me. It claims to create different fingerprints for different accounts. Or so I think. Not clear. They also have Browser fingerprint test by Iphey.com that displays many of the data points used to create fingerprints.
Unrealistic Defense: Turn off JavaScript in your web browser. Easier said than done. Without JavaScript most websites will break. The only way to even attempt this defense is to use more than one web browser. Disable JavaScript in the one where you need privacy and use another browser when you don't mind being tracked.
No defense: Private browsing mode does not prevent fingerprinting. Neither does a VPN or the Tor network. Blocking cookies also does nothing.
No defense: Chrome, of course, offers no defense. Tracking people is what Google does.

ARTICLES

June 18, 2025: Websites Are Tracking You Via Browser Fingerprinting from the Department of Computer Science and Engineering at Texas A&M University. Quoting: "While prior works have studied browser fingerprinting and its usage on different websites, ours is the first to correlate browser fingerprints and ad behaviors, essentially establishing the relationship between web tracking and fingerprinting,"
June 14, 2022: Browser fingerprinting: what it is and how to protect yourself by Mike Williams For Tech Radar. Quoting: "Browser fingerprinting is probably top of the ‘most dangerous’ tracking charts right now, because it's accurate, hard to spot, and many browsers do almost nothing to keep you safe."
October 2019: Think you're anonymous online? A third of popular websites are fingerprinting you by Geoffrey A. Fowler in the Washington Post 500 popular websites were tested to see if they did fingerprinting. Some of the hardest things to fingerprint are iPhones, iPads and Macs running the Safari browser.
How do trackers work from the EFF. This article has no date which is shamefully amateurish. There is no mention of the Mullvad browser so this must have been written before 2023.

See also the topic of web browsers on this site.

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Note: This content was moved to its own page on February 21, 2025. The creation date below is for the page itself, not for the content. That said, some content updates were also made on the 21st.
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