The Custodians App is a platform for geo-localising, reporting, and coordinating remedial action for all the environmental challenges the Earth is facing. It is a citizen-science application that empowers everyone to be part of the change, providing decentralised information on locations where rubbish and plastic are scattered in nature, abnormal water discharges occur, hydrocarbon leaks are present, or other environmental issues arise. The Custodians are those who, in their daily lives, are committed to the preservation of nature and the future of the next generations. With The Custodians App, environmental problems are transformed into "challenge, solution, action".