Azido-PEG5-succinimidyl carbonate is a PEG derivative containing azide and succinimidyl carbonate moieties. The azide can undergo copper-catalyzed Click Chemistry reactions with alkynes, DBCO and BCN. The succinimidyl carbonate is a good leaving group and commonly reacts with amine nucleophiles. The hydrophilic PEG linker increases the water solubility of the compound.