  Many processes during the evolution of protoplanetary disks and during planet
formation are highly sensitive to the sizes of dust particles that are present
in the disk: The efficiency of dust accretion in the disk and volatile
transport on dust particles, gravoturbulent instabilities leading to the
formation of planetesimals, or the accretion of pebbles onto large planetary
embryos to form giant planets are typical examples of processes that depend on
the sizes of the dust particles involved. Furthermore, radiative properties
like absorption or scattering opacities depend on the particle sizes. To
interpret observations of dust in protoplanetary disks, a proper estimate of
the dust particle sizes is needed.
  We present DustPy - A Python package to simulate dust evolution in
protoplanetary disks. DustPy solves gas and dust transport including viscous
advection and diffusion as well as collisional growth of dust particles. DustPy
is written with a modular concept, such that every aspect of the model can be
easily modified or extended to allow for a multitude of research opportunities.
