  Massive and very massive stars can play important roles in stellar
populations by ejecting strong stellar winds and exploding in energetic
phenomena. It is therefore imperative that their behavior be properly accounted
for in synthetic model populations.
  We present nine grids of stellar evolutionary model sequences, together with
finely resolved interpolated sequences and synthetic populations, of stars with
9-500 Msun and with metallicities ranging from Galactic metallicity down to
1/250 Zsun. The stellar models were computed with the Bonn evolutionary code
with consistent physical ingredients, and covering core hydrogen- and core
helium-burning phases. The interpolation and population synthesis were
performed with our newly developed routine 'synStars'. Eight of the grids
represent slowly rotating massive stars with a normal or classical evolutionary
path, while one grid represents fast-rotating, chemically homogeneously
evolving models. The grids contain data on stellar wind properties such as
estimated wind velocity and kinetic energy of the wind, as well as common
stellar parameters such as mass, radius, surface temperature, luminosity,
mass-loss rate, and surface abundances of 34 isotopes. We also provide
estimates of the helium and carbon-oxygen core mass for calculating the mass of
stellar remnants.
  The Bonn Optimized Stellar Tracks (BoOST) project is published as simple
tables that include stellar models, interpolated tracks, and synthetic
populations. Covering the broadest mass and metallicity range of any published
massive star evolutionary model sets to date, BoOST is ideal for further
scientific applications such as star formation studies in both low- and
high-redshift galaxies.
