The<unk>  Metabolite and Chemical Entity Database is the largest repository of experimental tandem mass spectrometry data acquired from standards. The tandem mass spectrometry data on over 860,000 molecular standards (as of January 4th 2022) is provided to facilitate the identification of chemical entities from tandem mass spectrometry experiments. In addition to the identification of known molecules it is also useful for identifying unknowns using its similarity searching technology. All tandem mass spectrometry data comes from the experimental analysis of standards at multiple collision energies and in both positive and negative ionization modes.<unk>  serves as a data management system to assist in metabolite and chemical entity identification by providing public access to its repository of comprehensive MS/MS metabolite data.<unk> 's annotated list of molecular standards include metabolites and other chemical entities, searching<unk>  can be done based on a molecule's tandem mass spectrometry data, mass, chemical formula, and structure within the<unk>  website. Each molecule is linked to outside resources such as the Kyoto Encyclopedia of Genes and Genomes (KEGG) for further reference and inquiry. The<unk>  database was developed and is maintained solely by the Siuzdak laboratory at The Scripps Research Institute.
METLIN
DESMOND 
AETX
KHAT
IOMAI
CGM
HOHMS
DRACO