A thorough characterisation of an exoplanetary system includes also studying the evolution of planetary atmospheres. To this end, we developed a custom tool to estimate the atmospheric content of exoplanets at the dispersal of the protoplanetary disk accounting for the present day system observables. In detail, our tool relies on planetary evolutionary models relating mass, radius and equilibrium temperature with the expected atmospheric mass fraction and mass loss rate, the latter derived from hydrodynamic simulations. The evolution is significantly influenced by the stellar activity level, therefore we employ theoretical stellar evolutionary models to evaluate the high-energy emission over time. Our tool works in a Bayesian framework, it requires to set input priors based on observations, it generates millions of planetary evolutionary tracks, and it retrieves the posterior distributions of the parameters of interests, namely the planetary atmospheric mass fraction at the time of disk dispersal and the evolution of the host star's rotation rate. We successfully applied this framework to a number of recently discovered planets and it is a promising tool for improving our understanding of both planet formation and stellar evolution on the basis of PLATO detections.