To curtail CO2 emissions, many changes of steel production chains are needed. Investments have to be planned while future framework conditions are unknown. The increasing replacement of fossil sources with intermittent renewable energy (in particular H2) will increase fluctuations in energy availability and prices. Injecting H2-rich gases in the BF and replacing a BF with DR-EAF significantly affect the site-wide gas supply. Process integration will need re-optimisation, in particular with respect to gas and energy flows. Current ICT tools are not able to address these new tasks due to lack of flexibility and optimisation capability. These challenges are addressed in AgiFlex, which exploits a highly innovative multi-agent approach for production and energy management on a completely new level. This tool monitors and controls processes, conditions and resources and optimises process integration and gas and energy flows along the complete steel production chain. AgiFlex develops digital twins for existing and new production steps and couples them into a framework for holistic optimization. The new system is demonstrated as “digital AgiFlex plant“ at two industrial sites in TRL 7 and is thoroughly verified with existing data and tools. By this, it will immediately decrease the carbon footprints. Scenarios for future framework conditions (e.g., availability and costs of renewable energies, future plant states) are studied with the new ICT tool and different options for injection, utilisation, recycling or export of gases are assessed considering process needs, safety issues and economic aspects. Decarbonisation strategies with optimised process integration are derived for different steps of plant transition to low carbon technologies. This includes also possible control measures for demand-side response. The easy and flexible transfer of the modular tool to other plants will be proven, supported by intensive communication and dissemination actions.