Combinatorial glycan composition determination has been demonstrated to be suitable for identifying glycans in MS acquisitions of glycan-containing samples. With a diverse range of sample preparation, acquisition methods, and vendors, profiling glycans by their precursor mass is a robust initial approach with minimal assumptions. To enhance the identification of glycan precursors in acquired MS data, we developed an open-source Windows application for the rapid extraction of precursor m/z values from the mzML file format, a vendor neutral file type that enables cross-platform compatibility. Many aspects of the glyco-analytical pipeline can affect the resulting m/z values observed in these mzML files, and as a result, GlyCombo is run through a GUI that requests user specifications regarding the mass error, reducing end format, glycan state, and expected monosaccharide ranges (Fig ). Unlike GlycoMod, we also provide hexosamine (i.e. isomerically ambiguous glucosamine) as a new monosaccharide for combinatorial analysis, enabling the analysis of biomedically relevant polysaccharides such as heparan sulfate . In addition to a large list of monosaccharide presets, including sialic acid derivatives, a maximum of five custom monosaccharides can be specified to ensure coverage of most applications.