Azido-PEG7-NHS ester is a PROTAC linker that falls under the PEG category and is used for synthesizing PROTAC molecules. This compound acts as a click chemistry reagent, featuring an Azide group, which can undergo a copper-catalyzed azide-alkyne cycloaddition reaction (CuAAc) with molecules containing an Alkyne group. Additionally, it can participate in strain-promoted azide-alkyne cycloaddition (SPAAC) with molecules that contain DBCO or BCN groups.