Updated publication reference for PubMed record(s): 32103093. Here we report a simple and versatile approach for domain mapping of complex mixtures of glycosaminoglycans (GAGs), GAGDoMa. The approach is based on orthogonal enzymatic depolymerization of the GAGs, generating internal oligosaccharide, non-reducing end, and linkage region GAG domains, nanoflow reversed-phase dibutylamine ion-pairing chromatography and negative mode higher-energy collision dissociation (HCD) MS/MS. GAGDoMa provides a detailed insight into the GAGome, and will be an important tool for the understanding of GAGs in cellular physiology and pathology.