After the Fukushima accident, initiatives emerged from the public to carry out themselves measurements of the radioactivity in the environment with various devices, among which smartphones, and to share data and experiences through collaborative tools and social networks. Such measurements have two major interests, on the one hand, to enable each individual of the public to assess his own risk regarding the radioactivity and, on the other hand, to provide “real time” data from the field at various locations, especially in the early phase of an emergency situation, which could be very useful for the emergency management. The objective of the OpenRadiation project is to offer the public the opportunity to perform measurements of the radioactivity using connected dosimeters on smartphones. The challenge is to operate such a system on a sustainable basis in normal situations and being useful in an emergency situation. In normal situations, this project is based on a collaborative approach with the aim to get complementary data to the existing ones, to consolidate the radiation background, to generate alerts in case of problem and to provide education & training and enhanced pedagogical approaches for a clear understanding of measures for the public. In case of emergency situation, data will be available “spontaneously” from the field in “real time” providing an opportunity for the emergency management and the communication with the public. The practical objectives are to develop i) a website centralising measurements using various dosimeters, providing dose maps with raw and filtered data and offering dedicated areas for specific projects and exchanges around data and ii) a dosimetric app using a connected dosimeter. This project is conducted within a partnership between organisms’ representative of the scientific community and associations to create links with the public. This project is conducted within a partnership between organisms’ representative of the scientific community and associations to create links with the public. The website is available since October 2017 and more than 100 000 measurements were performed by about 80 users.