SPVIEW, the free and open source spectral viewer
SPVIEW is a cross-platform application for 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 handle spectra in various formats (including HITRAN format). The lines can be assigned graphically using the mouse. Assignments can also be changed or deleted. Local simulations can be performed, for example, to facilitate assignment to partially resolved line groups. SPVIEW is also capable of producing peak lists from an experimental spectrum.
For MacOS users
The app is not signed, you will need to update the quarantine attribute of the app file by doing:
xattr -d com.apple.quarantine /Applications/Spview.app