4-Chloro-3-indoxyl-1,3-diacetate is a fluorogenic or chromogenic substrate used in food testing. It is also an enzyme substrate that can be used to detect the presence of bioluminescence. 4-Chloro-3-indoxyl-1,3-diacetate has been shown to have high purity and high quality for use in diagnostic kits. 4-Chloro-3-indoxyl-1,3-diacetate is a ligand that is conjugated with other molecules to form complexes for use in fluorescence and chemiluminescence experiments.