The EU-funded REACHOUT project strengthened cooperation between different European cities through co-creation centers to create a comprehensive and flexible set of resources (Triple-A Toolkit). The toolkit aims to support communities in understanding climate-related risks, designing adaptation options and transformations, and taking action to build resilience. This policy brief aims to share key lessons and case studies from REACHOUT City Hubs approaches to engage in co-creation in the development of climate services and tools in the urban environment.