Fat has a major economic importance in the beef industry. It affects all the meat food chain steps: from the farmer to the consumer, through the slaughterer-processor or the distributor. However, nowadays, managing fat in beef is difficult, in particular because no tool was able to measure fat in meat in real time, in a reliable, economical and non-destructive way. Using image analysis methods based on Artificial Intelligence, the Meat@ppli smartphone application predicts the fat content of beef, from a simple photo of the primary cut of the carcass captured with the smartphone. By providing the intramuscular fat content (marbling) of the rib eye and the fat content of the entire rib, it objectively evaluates the fat at the primary cut of the carcasses. It can thus be used both for the orientation of carcasses on the various commercial circuits and as a massive phenotyping tool for the selection of the animals of the future. Meat@ppli was designed by Institut de l'Elevage, INRAE and Institut Pascal.