A significant number of reactions in BRENDA are unbalanced, or could not be mapped via reaction rules because the entry itself was flawed. Usually, the reactant was correctly extracted from literature, but the product was not entered correctly, often because it is not explicitly mentioned in the original publication. For example, the reaction isopropanol + NAD+ = isopropylaldehyde + NADH + H+, EC 1.1.1.103 wrongly lists isopropylaldehyde as product, although the oxidation of isopropanol clearly should lead to propanone. The same mistake (a ketone falsely named as aldehyde, which introduces an additional carbon atom) occured hundreds of times in BRENDA for many different reactions, implicating a systematic error in their reaction curation. To correct for unmapped or unbalanced reactions, we propose probable reaction outcomes to correct reactions based on the reaction rules occurring in the same EC class and the similarity of both reactants and products via Tanimoto similarities of Morgan fingerprints as implemented in RDKit. These reactions are flagged as 'suggested', and may be filtered by the user. Both reactant and product similarities were taken into account to identify similar reactions based on the reactants, and then choose the most probable product after rule application, which often leads to multiple possible products due Frequent rules: