  The study of massive stars in different metallicity environments is a central
topic of current stellar research. The spectral analysis of massive stars
requires adequate model atmospheres. The computation of such models is
difficult and time-consuming. Therefore, spectral analyses are greatly
facilitated if they can refer to existing grids of models. Here we provide
grids of model atmospheres for OB-type stars at metallicities corresponding to
the Small and Large Magellanic Clouds, as well as to solar metallicity. In
total, the grids comprise 785 individual models. The models were calculated
using the state-of-the-art Potsdam Wolf-Rayet (PoWR) model atmosphere code. The
parameter domain of the grids was set up using stellar evolution tracks. For
all these models, we provide normalized and flux-calibrated spectra, spectral
energy distributions, feedback parameters such as ionizing photons, Zanstra
temperatures, and photometric magnitudes. The atmospheric structures (the
density and temperature stratification) are available as well. All these data
are publicly accessible through the PoWR website.
