AnyPetro is a Matlab-based, GUI-controlled software for adjusting the parameters of arbitrary and non-linear petrophysical models to laboratory data. A Gauss-Newton scheme is applied for the minimization of a damped least-squares objective function. Thereby the Jacobian matrix is calculated explicitely with the perturbation method. Data weighting, model parameter transformations and different regularizations are provided. The petrophysical model resp. the forward operator is introduced by the user in the form of a short text file. Example data files and forward operators as well as Matlab App and standalone installers are provided. The software tool has been developed for and successfully applied to the fitting of various petrophysical data sets (e.g. porosity, specific surface, electrical conductivity, spectral induced polarization) from fluid, unconsolidated, solid and crushed samples to non-linear, multi-parameter models (e.g. electrical CO2-water interaction, Debye Decomposition, crushed rock conductivity).