The present invention provides systems and methods for authenticating access requests from user devices by presenting one of a plurality of graphical user interfaces selected depending on a perceived risk of fraud associated with the devices. User devices are identified with fingerprinting information, and their associated risks of fraud are determined from past experience with the device or with similar devices and from third party information. In preferred embodiments, different graphical user interfaces are presented based on both fraud risk and, in the case of a known user, usability. In preferred embodiments, this invention is implemented as a number of communicating modules that identify user devices, assess their risk of fraud, present selected user interfaces, and maintain databases of fraud experiences. This invention also includes systems providing these authentication services.