6-Azidohexanoic acid is a six carbon saturated fatty acid with an ω-terminal azide group. This building block that can be reacted with primary amine groups in the presence activators (e.g. EDC, or DCC) forming a stable amide bond. The terminal azide group allows conjugation with compounds containing alkyne groups through a copper(I)-catalyzed cycloaddition reaction, also known as click chemistry. 6-Azidohexanoic acid is commonly used as a linker that is first acylated to one compound to create a derivative that can then be joined to another compound using click chemistry.