... to drive functionality. It comprises 3 parts: (1) the core Spectrum Viewer displays peptide-spectrum matches and implements zooming, mouse-over peaks to highlight matching parts of peptide, mouse-over parts of peptide to highlight matching peaks, export SVG, and API; (2) the Auxiliary Annotator matches peptide to spectrum for given parameters and prepares the data for the Viewer; (3) these reside on a web page that provides the user control over peptides, spectra and other parameters e.g. linker mass.