I just tried it out, and 1) their definition of &quot;nearly unique&quot; was &quot;1 in 2068276.0 browsers&quot;, which I agree is not good but also seems to be a non-intuitive rating scale, and 2) I swear from looking at the results that they are failing to take into account cross-variable correlations (but have not dug into this enough to be sure, so don&#x27;t quote me on this or anything: do your own research), by which I mean that each entropy source is considered in isolation, even though my screen size and user agent (which tells you I have an iPhone running iOS 8.4) should massively discount the screen size statistic (which is effectively just telling you I have an iPhone 6), as well as my &quot;browser plugin details&quot; (as they are likely the same for every single iPhone), and probably to some lesser extent even my time zone (I live in California, where I would imagine having a semi-recent iPhone would be more common, though I could see an argument that my using an out-of-date firmware is less common ;P). FWIW, if this is not yet including any knowledge of my IP address, then one in millions is brutal, as I am probably one of only a small handful of people in Isla Vista that has this specific iPhone configuration.