The aim of the POPCAT project was to develop a reliable cost-benefit model, built on accurate data reflecting the dynamics of cat populations in Flanders. The imposed model for the development of the simulator was the "Høgasen cost-benefit model for free-roaming dog populations". The two main questions of the project were "What modifications are needed to this existing model (Høgasen et al. 2013) With regard to cats and the Flemish context?" And "Which management methods for the cat population of individual cities and municipalities in Flanders are the most favorable in the area of ​​cat welfare, public nuisance and financial costs?". After creation of the POPCAT simulator, a test phase was introduced. Based on the user experience and feedback, the simulator and the accompanying manual were further optimized in a user-friendly way.