Abstract-This paper discusses the implementation of a software system prototype to run online experiments regarding differences in the reaction of newsletter receivers to absolute and relative rebates. Therefore a split-run component was added to an online cashback system to gather experimental data on their behavior. The prototype was then evaluated from a functional point of view by executing and verifying several split-run tests. The usability was evaluated using a standard questionnaire approach (ISONORM 9241/110). Having passed both tests, we offer the prototype to the scientific community as a stable platform to run further experiments.Index Terms-Cashback, consumer behavior, rebates, split-run test.