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’ve 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 in the browser’s nightly and beta builds for testing.

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.

Mozilla introduced Enhanced Tracking Protection last year

Firefox is not the only browser to attempt to block this kind of tracking. At WWDC 2018, Apple announced that it plans to build anti-fingerprint tracking into its Safari browser.

In addition to blocking fingerprint tracking, Firefox will also soon explicitly block cryptomining scripts from using your computer’s resources. However, according to Bleeping Computer, the browser has technically been able to block many of these scripts since late 2017 as part of its existing blocks on abusive ad trackers. The change here is that the browser is now explicit about blocking these scripts, and you’ll be able to turn blocking off for just cryptominers 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 (although it’s turned off by default).

The browser’s new anti-tracking technology is powered by Disconnect, which has provided a list of domains that serve these abusive scripts. Disconnect also currently offers a Chrome Extension that offers similar anti-tracking services on Google’s browser. By default, Google’s browser only offers the option to send Do Not Track requests. This option is turned off by default, and many sites will ignore it anyway.

Firefox’s new features will be available in the browser’s Nightly builds in version 68 and its Beta builds in version 67. Both of the new options are currently disabled by default, but Mozilla plans to make them opt-out for Nightly builds in the coming weeks. For now, in order to turn them on, you should head into the “Privacy & Security” tab of the Preferences menu, select the “Custom” section within “Content Blocking,” and tick the boxes next to the “Cryptominers” and “Fingerprinters” options.