Browser fingerprinting as a tracking technique to recognize users based on their browsers’ unique features or behavior has been known for more than a decade. We present the results of a 3-year online study on browser fingerprinting with more than 1,300 users. This is the first study with ground truth on user level, which allows the assessment of trackability based on fingerprints of multiple browsers and devices per user. Based on our longitudinal observations of 88,000 measurements with over 300 considered browser features, we optimized feature sets for mobile and desktop devices. Further, we conducted two user surveys to determine the representativeness of our user sample based on users’ demographics and technical background, and to learn how users perceive browser fingerprinting and how they protect themselves.
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