A computer program has been developed for fitting EPR data with multiple free radicals as formed in biochemical and chemical spin-trapping systems. Simulation of these spectra requires as many as 40 independent parameters, creating a chaotic analysis environment. Accurate simulation of these systems is essential for correct identification of the free radicals, which often show only slight differences in spin-Hamiltonian parameters. This method consists of rule-based perturbations with trial and error calculations and has proven successful in several applications. Details of the algorithm, example data, and a discussion of the difficulties of this analysis are presented in this report.