# Is AmIUnique accurate? It depends who it counts > AmIUnique measures its own visitors accurately, and they are not the web. Read which attribute sits at 0.01%, not the headline that says you are unique. Source: https://mosaicbrowser.com/blog/is-amiunique-accurate ## AmIUnique compares you with people who visit AmIUnique AmIUnique measures its own visitors accurately, and they are not the web. Read which attribute sits at 0.01%, not the headline that says you are unique. ![0.01%: Read the rarest row, not the headline](https://mosaicbrowser.com/covers/is-amiunique-accurate.webp) AmIUnique is accurate about the people it measures, and those people are not the web. It compares your browser with fingerprints left by its own visitors, a crowd that skews towards researchers, developers and privacy-minded users. So "you are unique" is a true statement about that table and a weak one about any site you actually use. The useful part of the page is lower down: which single attribute sits near 0.01%, and why. ## Who AmIUnique compares you with AmIUnique is a research site that began at Inria in France, run by researchers who study browser fingerprinting. Every visit adds a fingerprint to its dataset, and the results page compares yours with all of them. In 2016 Laperdrix, Rudametkin and Baudry published "Beauty and the Beast" at the IEEE Symposium on Security and Privacy, built on 118,934 fingerprints from the site's own visitors. About 90% of the desktop browsers in it were unique, and 81% of the mobile ones. Two years later the same group measured somewhere else. In "Hiding in the Crowd" (The Web Conference, 2018), Gómez-Boix, Laperdrix and Baudry collected 2,067,942 fingerprints from one of France's most visited websites, using the same attributes. Only 33.6% were unique. The authors' own conclusion was that the audience plays a large part in how effective fingerprinting is. Same attributes, same researchers, and uniqueness fell by well over half when the visitors were ordinary readers of a news site rather than people who had gone looking for a fingerprint test. That is the honest answer to "is AmIUnique accurate": the measurement is sound, and the sample is self-selected. Mosaic is a desktop app Email yourself the link and open it on your computer. [How it works: Machines that exist](https://mosaicbrowser.com/features/real-fingerprints) ## What our profile and a stock Chrome both read AmIUnique is one of the public detectors in Mosaic's Detection tests. When we run that catalogue, an untouched Google Chrome on the same machine goes through the same page as a control. On 19 September 2026, the profile under test read: ``` Yes! You are unique among the 5522816 fingerprints in our entire dataset rarest attributes: Canvas 0%, WebGL Data 0%, User agent 0.01%, Content language 0.01% ``` The control got the same verdict. The untouched browser on the same Mac was "unique among the 5522842 fingerprints", the count having moved on by a few visits. That is the first thing to know about the headline: it does not separate a browser somebody configured from one nobody touched, so it cannot grade either. That is why the row's verdict in our catalogue is `reference` rather than pass or fail, and the rule we read it by is written beside it: "No single attribute at '0.01% of visitors'. Being unique overall is unavoidable and fine; being the only browser in the world with your font list is not." ## How to read the attribute table instead Each row in the table says what share of the dataset has your value for that one attribute. Read the rare ones and ask why each is rare. There are three kinds of answer, and they need different responses. Rare because the dataset is old. The headline we quoted is the "All time" tab, which counts every fingerprint since the site opened, so anything that changes with each release, such as a browser version in the User-Agent, is rare there by arithmetic. A current Chrome version only gets common once enough people have visited with it. The page also has tabs for today, 7, 15, 30 and 90 days, and a recent window is the fairer comparison for a value like that. Rare because of the crowd. Our profile's language list was Austrian German first (`de-AT,de,en-US,en`), because the profile was matched to an Austrian exit. Among AmIUnique's visitors that list read 0.01%. Among the visitors of an Austrian shop it would be one of the most common lists there is. The value is right for the place; the table is the wrong place to judge it. Rare because something is wrong. This is the row that matters: a font list nobody else has, a screen size no device ships, a renderer string that no driver writes. A value that is rare because it is impossible is rare on every site, and a consistency scanner will find it whatever its crowd. Our profile's canvas and WebGL hashes both read 0%, and a hash is close to unique on any machine in a table this size, so a rare hash alone says little. What to check is whether the WebGL values agree with the GPU the browser claims. ## Use it beside a control The cleanest way to read AmIUnique is the way we read every detector: run your profile and an untouched browser on the same machine in the same session, and look only at what differs. A rare row that both share belongs to the machine or the crowd. A rare row only the profile has is a claim that profile made, and the thing to check. Why that control should be Google's own build and not a guess is in [the control that settles "is it our patches?"](https://mosaicbrowser.com/blog/the-control-is-googles-build). The EFF's test has the same crowd problem with a different crowd, and we worked through its number in [18.28 bits: what Cover Your Tracks' number measures](https://mosaicbrowser.com/blog/bits-of-identifying-information). What either page means for profiles that should stay stable rather than random is in ['Randomized fingerprint' is the wrong goal on Cover Your Tracks](https://mosaicbrowser.com/blog/cover-your-tracks-randomized), and the values a page reads in the first place are listed under [browser fingerprint](https://mosaicbrowser.com/glossary/browser-fingerprint). ## Questions ### Is AmIUnique accurate? It accurately compares your browser with the fingerprints its own visitors have left since the site opened. Those visitors are people curious about fingerprinting, so how rare you are there is not how rare you are on an ordinary website. ### Why does AmIUnique say I am unique? Almost every browser is unique in a large table of combined attributes, and AmIUnique's all-time table runs to millions of rows collected over years. An untouched browser we tested was unique there too. The headline says little on its own. The per-attribute percentages underneath are the part to read. ### What does 0.01% mean on AmIUnique? That roughly one fingerprint in ten thousand in its dataset shares that one value with yours. An attribute that rare is worth asking about: is it rare because of your machine, because of something you changed, or because of who visits the site? ### Is AmIUnique better than Cover Your Tracks? They answer a similar question with different crowds. AmIUnique is a research project with an all-time dataset; Cover Your Tracks is the EFF's test and compares you with browsers it has seen recently. Both count only their own visitors. ## Related [18.28 bits: what Cover Your Tracks' number measures](https://mosaicbrowser.com/blog/bits-of-identifying-information): Bits of identifying information is log2 of how rare your browser is in the EFF's sample. 18.28 bits is about one in 318,000, and it is not a tracking score. ['Randomized fingerprint' is the wrong goal on Cover Your Tracks](https://mosaicbrowser.com/blog/cover-your-tracks-randomized): Cover Your Tracks praises a randomized fingerprint, but values that change on every load are a signal too. Profiles need one stable, normal browser each. [The control that settles "is it our patches?"](https://mosaicbrowser.com/blog/the-control-is-googles-build): Unpatched Chrome for Testing got the same IPHey verdict as our engine, so our patches were not the cause. Its voice list still differs from Chrome's. [Browser fingerprint: what a site can read about your machine](https://mosaicbrowser.com/glossary/browser-fingerprint): A browser fingerprint is the set of values a site reads about your browser and computer, which together recognize you without cookies. What goes into one. [Why hCaptcha gives some browsers a puzzle every time](https://mosaicbrowser.com/blog/hcaptcha-image-challenge-every-time): hCaptcha's challenge is its score. A puzzle every time usually means blocked cookies, a crowded VPN exit or a browser whose values disagree with each other. [Why every Mac's Chrome says Mac OS X 10_15_7](https://mosaicbrowser.com/blog/mac-os-x-10-15-7): Chrome froze the macOS version in its User-Agent, so every Mac claims 10.15.7. The real one is in Sec-CH-UA-Platform-Version, a hint sites must ask for. [Why the User-Agent says Windows 10 on Windows 11](https://mosaicbrowser.com/blog/windows-11-user-agent-windows-10): Windows 11 and 10 both send Windows NT 10.0 in the User-Agent. Only the platformVersion client hint, 13 or higher, says Windows 11. [Why Chrome's User-Agent says 0.0.0](https://mosaicbrowser.com/blog/chrome-user-agent-0-0-0): Chrome zeroes everything after the major, so the User-Agent says 0.0.0 and the build moves to Sec-CH-UA-Full-Version-List. A real build in the UA is a tell. ## Mosaic, on your own computer The browser this blog is about: its own Chromium, fingerprints from real machines and a proxy exit per profile. Free holds 3 profiles. Pro is $49 a month for any number. Mosaic is a desktop app Email yourself the link and open it on your computer.