  The stellar initial mass function (IMF) is critical to our understanding of
star formation and the effects of young stars on their environment. On large
scales, it enables us to use tracers such as UV or Halpha emission to estimate
the star formation rate of a system and interpret unresolved star clusters
across the universe. So far, there is little firm evidence of large-scale
variations of the IMF, which is thus generally considered universal. Stars form
from cores and it is now possible to estimate core masses and compare the core
mass function (CMF) with the IMF, which it presumably produces. The goal of the
ALMA-IMF large program is to measure the core mass function at high linear
resolution (2700 au) in 15 typical Milky Way protoclusters spanning a mass
range of 2500 to 32700 Msun. In this work, we used two different core
extraction algorithms to extract about 680 gravitationally bound cores from
these 15 protoclusters. We adopt per core temperature using the temperature
estimate from the PPMAP Bayesian method. A power-law fit to the CMF of the
sub-sample of cores above the 1.64 Msun completeness limit, 330 cores, through
the maximum likelihood estimate technique yields a slope of 1.97 +/- 0.06,
significantly flatter than the 2.35 Salpeter slope. Assuming a self-similar
mapping between the CMF and the IMF, this result implies that these 15
high-mass protoclusters will generate atypical IMFs. This sample is the largest
to date produced and analysed self-consistently, derived at matched physical
resolution, with per-core temperature estimates and cores as massive as 150
Msun. We provide the raw source extraction catalogues and the source derived
size, temperature, mass, and spectral indices in the 15 protoclusters.
