N-(Azido-PEG1)-N-bis(PEG3-t-butyl ester) is a small branched PEG linker containing an azide and two tert-butyl esters. The t-butyl ester can be deprotected under acidic or basic conditions for use in coupling with primary amines or other nucleophiles, while the azide is open for click chemistry with alkynes or strained cyclooctynes.