https://whatsmyname.app/ is an online tool that allows users to enumerate usernames across many websites[1][2]. It is the best free username enumeration tool available[2] and is hosted on a standalone website[2]. It can be used in combination with other tools such as https://whatsmyname.app or command line arguments[4]. The tool was created by Chris Poulter and is maintained by the official Twitter account @WhatsMyName[5].