  The package CosmoLib is a combination of a cosmological Boltzmann code and a
simulation toolkit to forecast the constraints on cosmological parameters from
future observations. In this paper we describe the released linear-order part
of the package. We discuss the stability and performance of the Boltzmann code.
This is written in Newtonian gauge and including dark energy perturbations. In
CosmoLib the integrator that computes the CMB angular power spectrum is
optimized for a $\ell$-by-$\ell$ brute-force integration, which is useful for
studying inflationary models predicting sharp features in the primordial power
spectrum of metric fluctuations. The numerical code and its documentation are
available at http://www.cita.utoronto.ca/~zqhuang/CosmoLib.
