MobilX is an application developed by the Institute of Radioprotection and Nuclear Safety (IRSN, ASNR since 2025) for those involved in the nuclear or radiological crisis in an exercise situation. Its objective is to improve the realism of radioactive contamination measurements during nuclear crisis exercises. The application uses the GPS position and the phone/tablet clock and displays in real time the radiological quantities scripted specifically for the exercise, thus allowing specialized teams to train for their missions of measuring radioactive contamination or dose rate while minimizing exercise bias.