Firefox is testing a new anti-tracking feature that will prevent sites from being able to ‘fingerprint’ your browser and track you, even after you have cleared your cookies. In addition, the browser will now explicitly block cryptocurrency mining scripts that attempt to hijack your computer’s resources in order to mine digital currency. Both features will initially be available only to testers.
Fingerprinting describes the way sites and online advertisers are able to track you based on aggregating numerous tiny details about your system configuration, ranging from your operating system to your system fonts and even your screen size. Even if you have tracking turned off, services can use these tiny clues to build a unique fingerprint for you and use this to track you across sites.
In addition to blocking fingerprint tracking, Firefox will also soon explicitly block cryptomining scripts from using your computer’s resources. The browser will explicitly block these scripts, and you will have to turn blocking off if you so choose.
The new features are part of a broader move by Mozilla to increase user privacy. Last year, Firefox 63 introduced Enhanced Tracking Protection, a feature that blocks third-party trackers, but you have to turn on the feature, as by default it is turned off.