Mozilla cut unique browser fingerprints from 75% to 46% in Firefox 143
A comprehensive study of how fingerprintable users are
Mozilla measured browser fingerprinting across nearly 25 million Firefox users using privacy-preserving OHTTP telemetry. The study found that uniqueness is driven by a small set of high-impact characteristics—80% of users flagged as unique by Fingerprint Pro were identified after just 8 of over 50 metrics. The protections shipped in Firefox 143 reduce uniquely identifiable users from 75% to 46% while maintaining web compatibility, and the team argues that cohort size, not just uniqueness, should guide defense design.
For a default, compatibility isn't a trade-off against privacy—it's a precondition for it.
- M95D
> Protections that ship have to keep the web working
I don't agree. I activated most of the protections. If a site breaks, then I don't get to see it. That's OK. No big loss. Users should fight their FOMO.
- gausswho
Ran their fingerprinting test.
CSS Colours SelectedItem and SelectedItemText was the only problematic one, and uniquely identified me to less than 0.0054 of Linux users.
Why?
- dt3ft
> Your browser is not comparable to the dataset, so we have avoided showing you inaccurate results.
Yup. Because I use my own browser. Built from scratch with exception of V8, Stylo html5ever, and a few other bits and bobs. A fresh new rendering engine in Rust and all. Not a fork of any existing engine. Native support for uBlock Origin filter lists and custom filters. It scores above ~20 in speedometer as of today and covers WPT about 89%. Will be publishing it soon as permissive open source.
- _factor
I wonder if this took into account GPU render-time fingerprinting? The minute timing differences in how you render an image are still used to identify you.
- ape4
I read they're not releasing the details - that seems good (for the public). Hopefully they're releasing it to privacy-friendly browser makers.