Fourier Transform Infrared (FTIR) spectral libraries enable the identification of unknown substances by comparing molecular fingerprints against established standards, with key resources including the SWGDRUG database, the NIST Chemistry WebBook, and specialized collections from the Kimmel Center. For specialized forensics or industrial needs, commercial databases like Wiley’s KnowItAll are used, while free, high-volume, and open-source options are also widely available for spectral analysis. Free IR spectra libraries can be downloaded from Nicodom Ltd. .