In recent decades, an ever-increasing number of institutional collections have begun to comprehensively digitise their collections and make the resulting catalogues available freely online. These online catalogues have brought to light a number of objects that may have previously never been displayed and have allowed scholars to better understand the nature and scope of collections around the world. As such, they are a valuable source of open access data for those interested in the trade in cultural heritage and history of collecting. Focussing on forged papyri, this chapter considers the communication of (in)authenticity in online collection catalogues to better understand the reliability of the information they provide. It will be shown that although issues with authenticity appear to be recorded more often than current research would perhaps suggest, the reasons for presenting material as either authentic or inauthentic are frequently not made clear. As such, when forgeries are mistakenly presented as authentic in these online catalogues, their authenticity appears secure and there is little indication to anyone working from the catalogue that there might be some form of issue.