How can you tell if soy sauce has gone bad?

How can you tell if opened soy sauce is bad or spoiled? The best way is to smell and look at the soy sauce: if the soy sauce develops an off odor, flavor or appearance, or if mold appears, it should be discarded.

How long is soy sauce good after opening?

one month
Soy sauce is another necessity. It’ll last around three years if unopened, but it should be used up within one month if refrigerated after opening.