CATALYST, an EU H2020 project, aspires to turn data centres into flexible multi-energy hubs, which can sustain investments in renewable energy sources and energy efficiency. Leveraging on results of past projects, CATALYST will adapt, scale up, deploy and validate an innovative technological and business framework that enables data centres to offer a range of mutualized energy flexibility services to both electricity and heat grids, while simultaneously increasing their own resiliency to energy supply. The adaptation and replication potential of the CATALYST solution will be demonstrated by carrying out four pilots in operational data centres, spanning through the full spectrum of data centre types, from fully distributed, HPC to colocation and legacy, and architectures, from large centralized versus decentralized micro data centres.