QPP Sim is a simple discrete event simulator aimed at helping and accelerating the study of Quality of Service (QoS), Priority, and Pre-emption (QPP) mechanisms and policies in LTE. The complexities of the LTE architecture have been abstracted in order to facilitate the rapid prototyping of schedulers, priority policies, and monitoring mechanisms, and enable comparative analyses of different approaches, solutions, and proposals. Available here: https://github.com/usnistgov/qppsim