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Due to the computational cost of calculating a great number of variations ofthe parameters, detailed radiative models of pulsar wind nebulae (PWNe) do notusually contain fitting algorithms. As a consequence, most of the models in theliterature are, in fact, qualitative fits based on visual inspection. This isparticularly true when complex, time-dependent models are considered. Motivatedby improvements in the computational efficiency of the current PWN models thatwere obtained in the last years, we here explore the inclusion of automaticfitting algorithms into a fully time-dependent model. Incorporating anefficient fitting tool based on the Nelder-Mead algorithm, we blindly findfitting solutions for the Crab nebula and 3C 58 with a time-dependent radiationmodel to compute the spectral and dynamical evolution of young and middle-agedPWNe. This inclusion allows us, in addition of more faithfully determining thequality of the fit, to tackle whether there exist degeneracy in the selectedPWNe models. We find both for Crab and 3C58, that the fits are well determined,and that no other significantly different set of model parameters is able tocope with experimental data equally well. The code is also able to consider thesystem's age as a free parameter, recursively determining all other neededmagnitudes depending on age accordingly. We use this feature to considerwhether a detailed multi-frequency spectra can constrain the nebula age,finding that in fact this is the case for the two PWNe studied.

How unique are pulsar wind nebulae models? Implementation of a multi-parameter, automatic fitting for time-dependent spectra