This work presents the molecular simulation program ms2 that is designed for the calculation of thermodynamic properties of fluids in equilibrium. With ms2, thermodynamic properties can be calculated for pure fluids and mixtures that consist of small electro-neutral molecules. Both molecular dynamics and Monte Carlo simulations can be performed. The calculation of thermal and caloric data for homogeneous states as well as vapor-liquid equilibria and transport properties is supported. ms2 is designed to achieve short response times on different hardware and straightforward handling. Feature tools facilitate the interpretation of input and output files.