GalRotpy models the dynamical mass of disk-like galaxies and makes a parametric fit of the rotation curve by means of the composed gravitational potential of the galaxy. It can be used to check the presence of an assumed mass type component in a observed rotation curve, to determine quantitatively the main mass contribution in a galaxy by means of the mass ratios of a given set of five potentials, and to bound the contribution of each mass component given its gravitational potential parameters.