Cyanine3B azide is utilized for click chemistry reactions, either by copper-catalyzed reactions with terminal alkynes or copper-free reactions with strained cyclooctynes. Cyanine3B is a yellow-emitting cyanine dye and an improved version of the Cyanine3 fluorophore, offering significantly higher fluorescence quantum yield and photostability. Due to its fixed conformation, Cyanine3B achieves the highest emission quantum yield among dyes of this wavelength. This non-sulfonated dye requires organic co-solvents (DMF, DMSO, or others) for effective labeling in aqueous solutions.