flexMIRT is a versatile program for unidimensional and multidimensional item response theory (IRT) calibrations, scoring analyses, and model-based simulations. With an adaptable syntax that allows for various combinations of model specifications, estimation constraints, and estimation choices, flexMIRT can handle almost all of the most popular IRT models for dichotomous and polytomous data. The software package also supports diagnostic classification models and multigroup and multilevel analyses. This review evaluates the software from a user's perspective as well as some of its calibration, scoring, and simulation capabilities. Two simulation studies are included: one demonstrates some basic simulation capabilities and the other provides some direct comparisons with BILOG-MG. The review suggests that flexMIRT is a very good product that is only likely to get better as new features and suggestions for improvement are implemented.