A β-D-N-acetylgalactosamine (GalNAcβ) ligand equipped with a terminal carboxylic acid through a short butyl spacer. The carboxylic acid can be activated to NHS, sulfo-NHS, or pentafluorophenyl (PFP) esters and reacted with amine-functionalized platforms or lysine residues on proteins and peptides to form stable amide bonds. This compound enables the construction of hepatocyte-targeted therapeutics and research tools that exploit the asialoglycoprotein receptor (ASGPR), which is highly expressed on liver hepatocytes and binds GalNAc-containing ligands with high affinity.