Yesterday, ProPublica reported on new research by a team at KU Leuven and Princeton on canvas fingerprinting. One of the most intrusive users of the technology is a company called AddThis, who are employing it in “shadowing visitors to thousands of top websites, from WhiteHouse.gov to YouPorn.com.” Canvas fingerprinting allows sites to get even more identifying information than we had previously warned about with our Panopticlick fingerprinting experiment.