Synthetic peptides are commonly used in biomedical science for many applications in basic and translational research. Here, we assembled a large dataset of synthetic peptides whose identity was validated using mass spectrometry. We analyzed the mass spectra and used them for method validation as well as the creation of ground truth datasets and cognate databases. Contact: Michele Mishto, Head of the research group Molecular Immunology at King’s College London and the Francis Crick Institute, London (UK). Email: michele.mishto@kcl.ac.uk,