  HEALPix -- the Hierarchical Equal Area isoLatitude Pixelization -- has become
a standard in high-energy and gravitational wave astronomy. Originally
developed to improve the efficiency of all-sky Fourier analyses, it is now also
utilized to share sky localization information. When used for this purpose the
need for a homogeneous all-sky grid represents a limitation that hinders a
broader community adoption. This work presents mhealpy, a Python library able
to create, handle and analyze multi-resolution maps, a solution to this
problem. It supports efficient pixel querying, arithmetic operations between
maps, adaptive mesh refinement, plotting and serialization into FITS --
Flexible Image Transport System -- files. This HEALPix extension makes it
suitable to represent highly resolved regions, resulting in a convenient common
format to share spatial information for joint multi-wavelength and
multi-messenger analyses.
