The EU Local Digital Twin (LDT) Toolbox is a flagship initiative of the European Commission that provides a modular, standards-based suite of tools designed to help cities and communities across Europe simulate, analyse, and plan urban environments more effectively. Built around interoperability, openness, and scalability, the toolbox enables local administrations to use digital twins for evidence-based decision-making, policy testing, and sustainable development strategies. It focuses on simulation—not real-time operations—allowing stakeholders to anticipate challenges and co-create smarter urban solutions.