We present a software package aimed at simulating photon-number probability distributions of a range of classical and non-classical states of light. This software can generate arbitrary probability distributions from user-defined mode structure of a light field. It can also solve the reverse problem, i.e., reconstructing the mode structure of a light field from a given probability distribution. The mode structure fully defines a light field. Thus it provides information about the source of light without having to directly access the source. The multimode fields simulated by this software include those comprised of a number of thermal modes, a Poisson mode, and single-photon modes. In addition, conjugated multimode sources (such as those created via parametric downconversion (PDC) or four-wave mixing (FWM)) can be simulated. This software provides for a nearly-perfect reconstruction of multimode fields comprised of several correlated and uncorrelated thermal and Poisson modes. The code is particularly effective at characterizing mesoscopic quantum states of light. This software can be modified to include other types of modes (i.e., governed by other statistical distributions), as needed.