interTwin co-designs and implements the prototype of an interdisciplinary Digital Twin Engine (DTE), based on a co-designed Blueprint Architecture. The Digital Twin Engine (DTE) is an open-source integrated platform underpinned by open standards, APIs, and protocols. It facilitates the development, implementation and exploitation of specific Digital Twins. • The Digital Twin Engine (DTE) infrastructure modules provide specific capabilities for implementing Digital Twins, such as federated data and computing resources needed for modelling and simulation tasks. • The Digital Twin Engine (DTE) core modules offer cross-domain capabilities, simplifying the creation and operation of data-intensive and compute-intensive DT applications. • The Digital Twin Engine (DTE) thematic modules (environment and physics) are add-ons providing capabilities tailored to the needs of specific application groups. They implement core functionalities for a DT but domain specific. They can evolve into core modules following successful adoption by multiple resource communities across different domains. • The Digital Twin Applications (discover our use cases) are user-centric implementations of DTs workflows, leveraging the DTE’s capabilities to meet specific use case requirements.