Cos4cloud is pioneering the integration of citizen science in the EOSC. By the end of the project the services Pl@ntNet-API, Cos4Bio, MOBIS, AI-GeoSpecies, FASTCAT-Cloud and AUTHENIX are registered in EOSC Marketplace, and Cos4Env, DUNS, AI-Taxonomist, GBIF-DL and FASTCAT-Edge are planned to be uploaded soon. Any existing citizen science observatory can select and install from the EOSC the technical services needed to improve its functionalities. The impact of the citizen science component in Cos4Cloud has been studied following the methodology developed by the EU-funded project MICS. According to the MICS project, Cos4Cloud scored highest in the Environment domain; with scores of 40 for environmental awareness – the attitude regarding environmental consequences of human behaviour – and 32 for environmental footprint. The MICS platform notes that Cos4Cloud goes to great lengths to promote environmental awareness and educate participants on environmental challenges (through the sustained efforts of WP8 Communication, Outreach and Stakeholder Engagement); and to measure improvements in participants' environmental attitudes, behaviour and knowledge (as part of activities in WP5 COS4CLOUD services in practice, and WP6 Networking, Training and Capacity Building). Cos4Cloud also scored highly in the Science and Technology domain, with 37 for scientific productivity and 33 for interdisciplinary science. This reflects the high number of peer-reviewed publications produced by the project, and the highly collaborative nature of the Cos4Cloud team; with technological developers working alongside social scientists and educators. The project scored well in both the Economy and Society domains. Cos4Cloud scored an impressive 42 for economic productivity, indicating an explicit improvement in economic productivity through “diversification, technological upgrading and innovation”; specifically, the creation of thirteen new services for citizen observatories. The project scores 26 for financial sustainability, due to a combination of positive aspects – the use of an exploitation plan, for example – and less positive economic aspects, such as the need for recurring investments in the technology developed. Cos4Cloud scored 34 and 30 for activeness – the level of cognitive engagement in participating citizen scientists – and involvement – the degree of participation in different stages of a process – respectively. This reflects the highly collaborative co-design and testing process that formed part of the development of the thirteen services, and their incorporation into citizen observatories. Regarding the impact assessment of Cos4Cloud in terms of the socio-economic impact, we can highlight in the societal dimension the creation of the first national education community network merging citizen science with environmental education, a network with more than 500 at the time of the end of the project. In the scientific and technological dimension, Cos4Cloud has set a precedent in using co-design in the context of citizen science and technology, as well as integrating co-design and Agile Methodologies to develop innovative citizen science services. This impact has been demonstrated to practice in the co-design of the Cos4Cloud services and with the the almost 1,000 views of the co-design guide in Zenodo and almost 500 downloads of the infographics on the Cos4Cloud website. Two city councils, one in Bogotá (Colombia) and another one in Barcelona (Spain) have used Cos4Cloud research and services for official purposes and that also shows the valuable impact that Cos4cloud could have in the future in the agency dimension. Finally, in the environmental dimension of impact, Cos4Cloud has helped to record more than 40,000 observations and created new standardised, qualified, cost-effective citizen science datasets for environmental sustainability. In summary, Cos4Cloud has positively impacted society, science and technology, policies, economic, and environmental dimensions. All indicators and impact products show that the project meets all the requirements for its impact to continue growing beyond the project's lifetime.