The research had the general objective of improving the sales management inside the vet Janavet in Trujillo with the implementation of a multiplatform mobile application. For this case, an investigation of a preexperimental degree was followed, for which data collection tools were used, such as the registration forms, which were validate by the judgment of experts, and their reliability, the Extreme Programming work methodology was used for the development of the software. The results obtained after the implementation were the rise of the level of service from 95.21% a 98.66%, the total net worth from S/16,517.61 a S/23,129.50, the average amount in soles bought by client from 162 a 248 and the number of clients from 162 a 248. This thesis is divided in introduction, state of the art, objectives, materials and methods, methodology for the development of the multiplatform mobile app, results, discussion and conclusions.