  We present a set of isochrone-tailored spectral libraries for analyzing
composite spectra of low-metallicity massive star clusters or starburst
galaxies. Specifically, we have computed non-LTE spectra for stars of all
initial masses for isochrones at metallicities, Z=0.006, 0.002,and 0.0004, with
and without considering rotation. These isochrones were constructed by the
Geneva group (Ekstr\"{o}m et al., 2011; Georgy et al., 2013; Groh et al., 2019;
Eggenberger et al. 2020). We also present a Python program for integrating
individual spectra for an arbitrary initial mass function.
