Quality of Experience (QoE) typically involves conducting experiments in which stimuli are presented to participants and their judgments as well as behavioral data are collected. Nowadays, many experiments require software for the presentation of stimuli and the data collection from participants. While different software solutions exist, these are not tailored to conduct experiments on QoE. Moreover, replicating experiments or repeating the same experiment in different settings (e. g., laboratory vs. crowdsourcing) can further increase the software complexity. TheFragebogen is an open-source, versatile, extendable software framework for the implementation of questionnaires - especially for research on QoE. Implemented questionnaires can be presented with a state-of-the-art web browser to support a broad range of devices while the use of a web server being optional. Out-of-the-box, TheFragebogen provides graphical exact scales as well as free-hand input, the ability to collect behavioral data, and playback multimedia content.