D6.3 Citizen-science toolbox and evidence hub (renamed as the Cos4Cloud Toolbox and Evidence Hub) has been developed as a legacy collection of different materials and resources. It will be a ‘one stop shop’ of Cos4Cloud best practice demonstrating project results, this is being collated within the following category themes: Training & capacity building resources: Cos4Cloud co-designed technological services Best practice guidelines & resources for COs: Citizen observatories working collaboratively Educational resources: Examples of citizen science school-based approaches Case studies: demonstrating Cos4Cloud success stories and best practice examples Evidence Hub: feedback, discussion threads / themes, participation and engagement activities The development of the Cos4Cloud Toolbox and Evidence Hub contributes to the delivery of Work Package 6 (WP6) Networking, (education), training and capacity building, led by the OU. This output contributed to creating and sharing best practice guidelines, training, capacity building and educational citizen science resources. The Cos4Cloud Toolbox & Evidence Hub was envisioned as a ‘one-stop-shop’ of Cos4Cloud best practice guidelines and materials for existing and future citizen observatory leaders incorporating case studies, training, capacity building and educational citizen science resources. The main goal of WP6 is to demonstrate new conceptual models for evidence-based knowledge exchange, capacity-building, best practice learning and engagement with and for citizen science, focusing on citizen observatories.