BODIPY-TS (also known as Thiol-green 2) is a highly efficient thiol-specific turn-on probe with a fast response. It incorporates a thiosulfonate scaffold as its thiol recognition unit. BODIPY-TS displays excellent selectivity, low detection limit, and quantitative reactivity towards thiols. Moreover, it exhibits low toxicity. Notably, BODIPY-TS exhibits excitation at 490 nm and emission at 515 nm.