This paper describes the set of tools developed within the OrganiCity environment to enable citizens incentivization and rewarding. Under the Experimentation as a Service paradigm, OrganiCity enables the agile definition and test of urban experiments in a co-creative way. In this sense, citizens engagement plays a key role to ensure the viability of the experimental services, so that they can eventually become a minimum viable product. In this sense, we will introduce a scalable and modular scheme for engagement metrics definition, so as to quantify the level of participation of citizens in experiments. Furthermore, the paper will describe how this monitor scheme is integrated within OrganiCity, leveraging the information provided by the different services implemented there.