One of the most common suggestions for enhancing your online privacy is deleting your browser cookies. However, recent research by Texas A&M University proves that this approach is no longer effective.
The study exposes how modern websites are secretly using browser fingerprinting to track people’s online activities. This is a unique method that creates a detailed profile from your browser’s behavior and device characteristics.
According to Nitesh Saxena, a cybersecurity researcher, professor of computer science and engineering, and associate director of the Global Cyber Research Institute at Texas A&M, fingerprinting has long been a major concern, but there was no concrete proof that websites were using it to track users, until now.
Websites can track your online activities even after deleting cookies
When you access a website, your browser reveals a lot about you, including your screen resolution, device model, system settings, time zone, plugins, and more. The combination of these data points creates a unique ‘fingerprint’ of your configuration, which can identify you even without cookies.
Unlike cookies, which you can delete or block, fingerprinting doesn’t leave traces you can erase. Most people are unaware that this type of surveillance exists, and even privacy-focused browsers can’t block it completely.
‘Think of fingerprinting as a digital signature that you don’t know exists,’ Zengrui Liu, co-author of the report and a former doctoral student in Saxena’s lab. ‘You may think you’re anonymous online, but your browser or device is quietly exposing you, ’ he added.
Linking fingerprinting to advertising
This research is groundbreaking, revealing the real-world application of browser fingerprinting, especially for online advertising and user tracking.
‘While previous studies have examined browser fingerprinting, this is the first to link it directly to ad behavior, establishing a clear connection between web tracking and fingerprinting, ’ said co-author Dr. Yinzhi Cao, associate professor of Computer Science and Technical Director of the Information Security Institute at Johns Hopkins University.
To determine whether websites use fingerprinting, the researchers created a tool called FPTrace, which analyzes how advertising systems react to variations in browser fingerprints.
Website tracking to target users
This tool enables the research team to go beyond the surface-level code. They examined how ad systems responded to the modification of the browser fingerprints.
The idea was straightforward: if fingerprinting plays a role in tracking, altering the fingerprint should impact how advertisers bid for ad space.
‘This analysis enabled us to uncover more than just the presence of fingerprinting – it allows us to see if it was being used to monitor and target users, which is typically harder to prove,’ said Jimmy Dani, Saxena’s doctoral student.
A stealthy website tracking system
Surprisingly, the researchers found out that users could still be tracked even after they cleared cookies. This matters because it demonstrates that fingerprinting doesn’t depend on traditional trackers; it works across multiple sessions and devices.
Moreover, the team observed shifts in bid values and a drop in HTTP records and syncing events when fingerprints were changed, indicating that users were being re-identified without their knowledge or consent.
Even more shocking, some websites linked fingerprinting to the backend ad bidding processes. This suggests that fingerprint-based profiles were being used in real-time, likely to personalize responses or share identities with third parties.
Disregard for privacy laws
Another alarming aspect of the research is how fingerprinting disregards privacy laws. For example, users could be silently tracked through fingerprinting, even if they’ve opted out of tracking under privacy laws like the General Data Protection Regulation (GDPR) and the California Consumer Privacy Act (CCPA).
These laws require companies to respect users’ decisions not to be tracked. Unfortunately, fingerprinting exists in a gray zone, operating silently in the background without visible notification or consent request.
Need for stronger privacy protections
Besides exposing the problem, the study points toward solutions. The researchers advocate for robust browser defenses and updated regulations to address fingerprinting, as existing privacy tools and policies are insufficient.
They also hope that their FPTrace framework could become a valuable tool for regulators to identify and investigate unauthorized fingerprinting practices.
Your browser’s digital fingerprint
This groundbreaking study, unveiled at the ACM Web Conference (WWW) 2025, shows the advancement of online tracking and the alarming gap in user awareness.
While deleting cookies seemed enough, browser fingerprinting shows that companies have devised new ways to track users.
This highlights the urgent need for new tools and stronger regulations to address this growing threat to privacy. Until then, the digital fingerprint left by your browser will continue exposing your personal details you’d never knowingly share.
