A new theoretical phase field-based formulation for predicting electro-chemo-mechanical corrosion in metals is presented. The model combines electrolyte and interface electrochemical behaviour with a phase field description of mechanically-assisted corrosion accounting for film rupture, dissolution and repassivation. The theoretical framework is numerically implemented in the finite element package COMSOL MULTIPHYSICS and the resulting model is made freely available. Several numerical experiments are conducted showing that the corrosion predictions by the model naturally capture the influence of varying electrostatic potential and electrolyte concentrations, as well as predicting the sensitivity to the pit geometry and the strength of the passivation film.