Azido-PEG1-amine is widely used in bioconjugation and pharmaceutical research due to its ability to link molecules selectively. The azide group readily participates in click chemistry reactions, especially copper-catalyzed azide-alkyne cycloaddition (CuAAC), making it ideal for labeling biomolecules such as peptides, proteins, and nucleic acids with fluorescent tags, drugs, or polymers. The short PEG1 spacer improves solubility and reduces steric hindrance, allowing efficient reactions in aqueous and organic media. It is commonly used in the development of antibody-drug conjugates (ADCs), targeted therapies, and diagnostic probes. Additionally, its terminal amine group enables further coupling to carboxylic acids or activated esters, offering versatility in multi-step conjugation strategies.