Methods and systems for detecting fraudulent activity are described. A user types in a web address in his or her browser to request a webpage from a server, and the server communicates the webpage to the user. The communicated webpage includes a document object model (DOM) inspector and/or a JavaScript (JS) namespace inspector. The DOM inspector and JS namespace inspector detect anomalous DOM elements and anomalous JS namespace elements respectively. The DOM inspector and JS namespace inspector discover objects on the rendered webpage that should not be there.