vibrations.cheminfo.org — IR and Raman spectra in your browserDraw or paste a structure and a GFN2-xTB geometry optimization, Hessian, normal modes, intensities and thermochemistry run on your own machine; nothing is uploaded. The tool needs JavaScript; these are the pages it offers:

Calculator — draw a structure, run it, read the bands

Collections — seven curated sets, with a guided tour

Directing groups
Inductive / mesomeric effect
Mesomeric effect
Gross selection rule
Ring strain
Steric effect
Theory vs. experiment

Validation — ten reference calculations, scored

About — what it computes, and what it borrows