In recent years, lots of research has been done on effective usage of natural gas; the first step in these processes is conversion of natural gas to Syngas. Natural gas reforming process by refomer FURNACE is commonly used for syngas and hydrogen production. In this paper, windows based software, RIPI-RefSim, is introduced. By using proper heat, mass, kinetic and thermodynamic models as well as effect of catalyst shape, the software has been developed for the reformer FURNACE simulation for syngas and hydrogen production. RIPI-RefSim could be used in three different modes (Rating, Simulation and Design) and provides user a detailed understanding of FURNACE performance, product characteristics, temperature, reaction rates and pressure drop profiles, heat loss, effect of catalyst shape, and etc.