The EU-funded REACHOUT project has boosted collaboration across various European cities through co-creation hubs to come up with a comprehensive and flexible set of resources (Triple-A Toolkit). The toolkit aims to support communities in understanding climate-related risks, the design of 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 co-creation when developing climate services and tools in urban environments.