Grape and apple acids, usually minor parts of acid blends. Weaker exfoliants than glycolic or lactic acid, with little evidence on their own.
Tartaric acid (from grapes) and malic acid (from apples) are alpha-hydroxy acids that turn up in multi-acid blends and 'fruit extract' complexes. They are larger and weaker than glycolic and lactic acid, and in many formulas they mainly adjust pH rather than exfoliate much.
When a label says just AHA, it rarely states which acids or how much; judge the product by its full ingredient list and stated pH, if any.
Nearly all clinical AHA evidence is for glycolic and lactic acid. Tartaric and malic acid have lab data and appear in combination products, but trials testing them alone are scarce, so their contribution to a blend is uncertain.
Reviews alpha-hydroxy, beta-hydroxy and polyhydroxy acids, their uses for photoaging, acne and pigmentation, and their effects on sun sensitivity, noting that their mechanisms of action still need clarification.