This paper deals with tests of general relativity (GR) in the Solar System using tracking observables from planetary spacecraft. We present a new software that simulates the Range and Doppler signals resulting from a given spacetime metric. This flexible approach allows one to perform simulations in GR as well as in alternative metric theories of gravity. The outputs of this software provide templates of anomalous residuals that should show up in real data if the underlying theory of gravity is not GR. Those templates can be used to give a rough estimation of constraints on additional parameters entering alternative theory of gravity and also signatures that can be searched for in data from past or future space missions aiming at testing gravitational laws in the Solar System. As an application of the potentiality of this software, we present some simulations performed for Cassini-like mission in post-Einsteinian gravity and in the context of MOND external field effect. We derive signatures arising from these alternative theories of gravity and estimate expected amplitudes of the anomalous residuals. © 2012 IOP Publishing Ltd.