A synthetic heparan sulfate (HS) / heparin-like disaccharide bearing glucuronic acid (GlcA) β1-4-linked to 2-N,6-O-disulfated glucosamine (GlcNS6S). The GlcAβ1-4GlcNS6S unit is a common feature of HS NA/NS transition domains and of the HS sequences that bind growth factors such as FGFs. Heparan sulfate (HS) and heparin are sulfated glycosaminoglycans found as components of proteoglycans. HS, in close proximity to cell surfaces and extracellular matrix proteins, plays essential physiological roles binding hundreds of proteins, and may play a role in SARS-CoV-2 infection through virus binding to ACE2; heparin is mainly found in mast cell secretory granules. Synthetic, structurally defined HS/heparin fragments are valuable probes for sulfation-pattern-dependent protein binding, anticoagulant and growth-factor signaling research, and as standards for analytical and structure-activity studies.