1. A non-transitory computer-readable medium storing computer-executable instructions, which when executed by a processor, cause a computing device to perform steps comprising: displaying a graphical overlay over at least a portion of a page displayed on a graphical user interface according to page data; receiving data inputted into the graphical overlay, the inputted data including analytic data type information indicating a specific type of analytic data to be collected; identifying program instructions from a library; modifying the identified program instructions based on the inputted data to enable them to collect the specific type of analytic data when executed; embedding the modified program instructions into the page data of the page under the graphical overlay so that, when the page is accessed, the embedded modified program instructions begin to collect the specific type of analytic data and cause the specific type of analytic data to be stored for subsequent review; receiving analytic data corresponding to the displayed page from a remote server; and displaying at least a portion of the analytic data in the graphical overlay based on the inputted data.