What the research found
A 2025 study analyzed behavioral fingerprinting, identifying users by habitual patterns in how they browse rather than by cookies or device details, tracking over 150,000 people across two years. The researchers found that after a privacy-protecting action like clearing cookies or switching networks, a user loses an average of 78 to 85 percent of their anonymity within the first 60 seconds of browsing, and 90 percent within 10 minutes, canceling out most of the protection the action was supposed to provide.
A separate 2024 study built a tool called FP-tracer to measure how often websites fingerprint visitors using techniques like canvas and audio analysis. It found high-intensity fingerprinting on 8 percent of the domains tested, with more moderate activity present on up to 75 percent, and confirmed that fingerprinting shows up close to five times more often in third-party scripts than first-party ones. The same research checked whether standard cookie consent banners offer any real protection against this specific technique. They don’t.
Why clearing cookies misses the real problem
Cookies and fingerprinting solve the same tracking problem in different ways. A cookie is a file stored on your device, delete it and the identifier is gone. Fingerprinting works by reading characteristics your browser and behavior already expose: screen resolution, installed fonts, typing rhythm, scroll patterns, browsing habits, none of which a cleared cookie touches. Deleting cookies removes one tracking method while leaving a second, less visible one intact.
A 2025 study went further, showing that modern CSS styling code alone, with no JavaScript running at all, could distinguish 97.95 percent of over 1,100 tested browser and operating system combinations. This works even inside restrictive settings like email clients that block scripts for the specific purpose of preventing this kind of tracking.
The practical takeaway
Cookie deletion is worth doing, but treat it as one layer, not a full reset. Browser extensions built to resist fingerprinting, and privacy-focused browsers that randomize or standardize the technical details fingerprinting relies on, address a gap that cookie clearing alone leaves wide open. If a service claims deleting cookies makes you anonymous again, that claim doesn’t hold up against how tracking works today.
This research measured technical capability and real-world prevalence, not what any specific company does with fingerprinting data right now. The tools exist and are already in use. Individual sites still vary in what they do with what they collect.
References
Crichton, K., et al. “Rethinking Fingerprinting: An Assessment of Behavior-based Methods at Scale and Implications for Web Tracking.” Proceedings on Privacy Enhancing Technologies, 2025. https://doi.org/10.56553/popets-2025-0158
Boussaha, S., et al. “FP-tracer: Fine-grained Browser Fingerprinting Detection via Taint-tracking and Entropy-based Thresholds.” Proceedings on Privacy Enhancing Technologies, 2024. https://doi.org/10.56553/popets-2024-0092
Trampert, L., et al. “Cascading Spy Sheets: Exploiting the Complexity of Modern CSS for Email and Browser Fingerprinting.” Network and Distributed System Security Symposium, 2025. https://doi.org/10.14722/ndss.2025.230238
