Cain performs stochastic and deterministic simulations of chemical reactions. It can spawn multiple simulation processes to utilize multi-core computers. It stores models, simulation parameters, and simulation results (populations and reaction counts) in an XML format. In addition, SBML models can be imported and exported. The models and simulation parameters can be read from input files or edited within the program. Solvers are implemented as command line executables, which makes it easy to launch batch jobs and simplifies the process of adding new solvers. Solvers include Gillespie's direct method, Gillespie's first reaction method, Gibson and Bruck's next reaction method, Tau-leaping, and Hybrid direct/tau-leaping.