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A new study presented at the ACM Web Conference 2025 has confirmed a long-suspected but difficult-to-prove method of online tracking: browser fingerprinting. This technique allows websites to quietly identify and follow users across the internet—even after they clear cookies or use privacy settings.
The research, led by Texas A&M University in collaboration with Johns Hopkins University, uncovered how websites are not only collecting detailed information about users’ browsers and devices, but also using that data to influence online advertising systems in real time.
Unlike cookies, which can be deleted or blocked, browser fingerprinting relies on subtle characteristics of a user’s device that are shared with websites – like screen resolution, time zone, operating system, and installed fonts – to build a unique profile. This profile acts as a kind of digital fingerprint that is difficult to disguise or erase.
According to TechXplore, what sets this study apart is its ability to show a direct link between fingerprinting data and ad system behavior. Using a novel tool called FPTrace, the researchers analyzed how changing a browser’s fingerprint influenced advertising responses. They found that altering these identifiers led to shifts in ad bidding values and a reduction in communication events between websites and third parties—strong signs that fingerprinting was being used to track users behind the scenes.
Even more troubling is the discovery that this tracking continues even for users who have opted out under privacy regulations such as the GDPR or California’s CCPA. Despite legal protections, their browsers were still being profiled and potentially targeted.
The research indicates that fingerprinting is not just widespread, but deeply embedded in modern ad systems, often operating without users’ knowledge or consent. The authors argue that current browser protections and privacy laws are insufficient, and they urge both technology developers and policymakers to take action.
The FPTrace framework offers a new method to investigate and expose these hidden practices, potentially giving regulators the tools they need to hold companies accountable for unauthorized tracking.
