Microfluidic devices have found many great applications in medicine, (bio-)chemistry, pharmacology, etc. Unfortunately, their design process is still in its infancy, and frequently results in a costly and time-consuming “trial-and-error” approach, where designs are derived by hand. In order to prevent this, design automation methods and simulation tools can be utilized that aid designers during the whole design phase. In this article, we present such a simulation tool that allows to simulate the behavior of droplet-based microfluidic devices and, by this, allows to validate the functionality of the device, even before the first prototype is fabricated.