We present the purpose, long-term development vision, basic design, detection algorithm and preliminary results obtained with the Cosmic Ray Extremely Distributed Observatory (CREDO) Detector mobile application. The CREDO Detector app and related infrastructure are unique in terms of their scale, targeting many form-factors and open-access philosophy. This philosophy translates to the open-source code of the app, open-access in terms of both data inflow as well as data consumption and above all, the citizen science philosophy that means that the infrastructure is open to all who wish to participate in the project. The CREDO infrastructure and CREDO Detector app are designed for the large-scale study of various radiation forms that continuously reach the Earth from space, but with the sensitivity to local radioactivity as well. Such study has great significance both scientifically and educationally as cosmic radiation has an impact on diverse research areas from life on Earth to the functioning of modern electronic devices. The CREDO Detector app is now working worldwide across phones, tablets, laptops, PCs and cheap dedicated registration stations. These diverse measurements contribute to the broader search for large-scale cosmic ray correlations, as well as the CREDO-specific proposed extensive air showers and incoherent secondary cosmic rays.