6-Azido-D-lysine is a click chemistry reagent that features an azide group, enabling it to undergo copper-catalyzed azide-alkyne cycloaddition reactions (CuAAc) with molecules containing an alkyne group. Additionally, it can participate in strain-promoted alkyne-azide cycloaddition reactions (SPAAC) with molecules that have DBCO or BCN groups. This chemical reagent is notable for its application in incorporating azide functionalities.