SPVIEW is a cross-platform application that allows graphical assignment of high-resolution molecular spectra. It is possible to load, display and manipulate experimental and simulated spectra (XY ASCII format) as well as stick spectra in various formats (including HITRAN format). Lines can be assigned graphically using the mouse. Assignments can also be modified or removed. Local simulations can be performed in order, for  instance, to help assignment in partly resolved line clusters. SPVIEW is also able to produce peak lists from an experimental spectrum.

It is freesoftware, you can change its source code and distribute your changes.