 Although it was initially developed to aid the design of neutron scattering instruments for the European Spallation Source (ESS) as the name implies, VITESS serves as a generic simulation tool for a large variety of neutron scattering instruments at all major pulsed or continuous neutron sources.It comprises all established instrument hardware such as neutron optics (e.g.guides, apertures, lenses), wavelength selectors (e.g.