Fud AI is a free, open-source AI calorie tracker and food scanner available for both iPhone and Android devices. Users can log their meals through various methods, including taking a photo, scanning a barcode, using voice commands, or typing manually. The app supports an extensive range of features, such as tracking macros and body fat, and integrates with Apple Health. It offers both a bring-your-own-key (BYOK) option for AI access and an optional iOS Premium mode for hosted AI services, with on-device processing available for supported iPhones using Apple Intelligence as a fallback.