Abstract <p>Antioxidants effectively prevent oxidation by forming non-toxic products, making them of interest to food scientists, health professionals, and the public. Vitamin C, recognized for its antioxidant properties, has traditionally been evaluated for its reducing power using UV-Vis spectrophotometry and smartphone applications, though the latter has faced methodological limitations. This study aimed to improve and validate smartphone-based methods for assessing the antioxidant activity of beverages using ferric reducing antioxidant power analysis. The results showed a strong correlation between the reducing power of vitamin C measured by UV-Vis spectrophotometry (<i>R</i>² = 0.9913) and smartphone applications (<i>R</i>² = 0.9823), suggesting that the developed smartphone method is a viable and effective tool for identifying the antioxidant properties of commercially available beverages.</p>