  (Abridged) Electron-molecule interaction is a fundamental process in
radiation-driven chemistry in space, from the interstellar medium to comets.
Therefore, knowledge of interaction cross-sections is key. While there has been
a plethora of studies of total ionization cross-sections, data is often spread
over many sources, or not public or readily available. We introduce the
Astrochemistry Low-energy Electron Cross-Section (ALeCS) database, a public
database for electron interaction cross-sections and ionization rates for
molecules of astrochemical interest. In this work, we present the first data
release comprising total ionization cross-sections and ionization rates for
over 200 neutral molecules. We include optimized geometries and molecular
orbital energies at various levels of theory, and for a subset of the
molecules, the ionization potentials. We compute total ionization
cross-sections using the binary-encounter Bethe model and screening-corrected
additivity rule, and ionization rates and reaction network coefficients for
molecular cloud environments for $>$200 neutral molecules ranging from
diatomics to complex organics. We demonstrate that our binary-encounter Bethe
cross-sections agree well with experimental data. We show that the ionization
rates scale roughly linearly with the number of constituent atoms in the
molecule. We introduce and describe the public ALeCS database. For the initial
release, we include total ionization cross-sections for $>$200 neutral
molecules and several cations and anions calculated with different levels of
quantum chemistry theory, the chemical reaction rates for the ionization, and
network files in the formats of the two most popular astrochemical networks,
the KIDA and UMIST. The database will be continuously updated for more
molecules and interactions.
