A dedicated web site can be found here.
The X-Shooter Spectral Library is a collection of 3000-25000 Å all stellar spectra observed at a resolving power of R = λ/Δλ ~ 10 000 with the medium-resolution spectrograph X-Shooter at the Very Large Telescope (VLT).
If you use this service in your research, please include the following acknowledgement in any resulting publications:
"Based on data from the The X-Shooter Spectral Library service developed by the Spanish Virtual Observatory in the framework of the IAU Comission G5 Working Group : Spectral Stellar Libraries".