  The unrivalled astrometric and photometric capabilities of the Gaia mission
have given new impetus to the study of young stars: both from an environmental
perspective, as members of comoving star-forming regions, and from an
individual perspective, as targets amenable to planet-hunting direct-imaging
observations. In view of the large availability of theoretical evolutionary
models, both fields would benefit from a unified framework that allows a
straightforward comparison of physical parameters obtained by different stellar
and substellar models. To this aim, we developed the Manifold Age Determination
for Young Stars (MADYS), a flexible Python tool for the age and mass
determination of young stellar and substellar objects. In this first release,
MADYS automatically retrieves and crossmatches photometry from several
catalogs, estimates interstellar extinction, and derives age and mass estimates
for individual objects through isochronal fitting. Harmonizing the
heterogeneity of publicly available isochrone grids, the tool allows one to
choose amongst 17 models, many of which with customizable astrophysical
parameters, for a total of $\sim 110$ isochrone grids. Several dedicated
plotting functions are provided to allow for an intuitive visual perception of
the numerical output. After extensive testing, we have made the tool publicly
available. Here, we demonstrate the capabilities of MADYS, summarizing
previously published results as well providing several new examples.
