Healthcare, accidents, and security are global issues. Citizen First Aid is a mobile app that allows fast handling of emergencies and better support of people in distress, victims of medical problems or aggression, or others requiring urgent help. Much of the population has access to smartphones with geolocation tools that could be harnessed to tackle these problems. The app enables victims to alert people able to help nearby and ask them for necessary items. If a person is having an asthma attack, for example, someone nearby might have the Ventoline he or she needs. This person can be notified and guided to the person in need to provide help until professional aid arrives. This could be adapted to many situations: aggression, car accidents, diabetics in need of insulin… . All around us, many people would be ready to intervene if alerted in time; these people have goodwill and, in some cases, knowledge of first aid, protection, specific medicine, and other skills that could be useful. This app provides great benefits: improving public health, encouraging civic behaviour, providing autonomy to the elderly or people with disabilities, and even saving lives.