Google is testing a new update for Chrome on Windows 11 aimed at strengthening privacy in Incognito Mode. The feature, called PrivacySandboxFingerprintingProtectionEnabled, is designed to block third-party scripts that use known device fingerprinting techniques to re-identify users across websites.
How it works
Once enabled, Chrome will prevent the loading of third-party scripts that attempt to collect unique identifiers via APIs such as Canvas, WebGL, font detection, or audio analysis. This would make it harder for advertisers to track users even without cookies.
The blocking will not target all potentially harmful domains. Instead, it will apply only to those on the Marked Domains List (MDL). A domain is flagged if it acts as a third party and attempts to extract unnecessary data from the user’s browser or device.
To implement this system, Google has proposed a small change to the Fetch specification, allowing browsers to introduce a standardized “deceptive” mechanism to block or protect requests after the usual security checks, such as CSP validation and mixed content checks.
For example, if a domain uses a third-party script capable of fingerprinting via Canvas, WebGL, or font checks and then sends a unique identifier, the site owner could match that identifier to display targeted ads — even without cookies. The new script blocking in Chrome’s Incognito Mode would prevent such scripts from loading.
Comparison with other browsers
Other browsers have already introduced tracking protections:
- Safari uses Intelligent Tracking Prevention (ITP) to block third-party cookies and related scripts.
- Firefox offers Enhanced Tracking Protection (ETP).
- Microsoft Edge includes Tracking Prevention.
While Safari and Firefox block tracking scripts more aggressively during regular browsing, Chrome’s approach is more cautious: the protection is list-based and limited to Incognito Mode only.
Availability
Google has clarified that this feature will be implemented exclusively in Chrome’s Incognito Mode and is not planned for all Chromium-based browsers.
The testing comes shortly after the release of Google Chrome 139, which introduced AI-powered search suggestions in the address bar and New Tab page, along with expanded options for creating custom quick search shortcuts.
While Google acknowledges that achieving truly anonymous browsing without traffic routing is nearly impossible, this new script-blocking system is another step toward stronger privacy protection for Chrome’s Incognito Mode.
