Two-page document to briefly present the OSTrails Interoperability Reference Architecture. What is it? The OSTrails Interoperability Reference Architecture defines how key OSTrails components, Data Management Plans (DMPs), Scientific Knowledge Graphs (SKGs), FAIR Assessment tools and DMP Evaluation services, interact within research workflows. It promotes interoperability without imposing rigid implementations, helping to avoid vendor lock-in. The Goal: By standardising OSTrails components while allowing flexibility, the architecture enables automation, reusability, and future-proof integration not only with the services that are part of the Architecture but also with any external systems that want to exchange information with OSTrails components, across research data services and tools. Useful links: OSTrails website: https://ostrails.eu/ OSTrails GitHub: https://github.com/OSTrails Documentation: https://docs.ostrails.eu/ Training resources: https://ostrails.eu/training About OSTrails: OSTrails aims to transform how research is planned, tracked, and assessed by embedding the FAIR principles and interoperability at the core of research workflows. The project's overarching goal is to support researchers, institutions, and funders in building a cohesive, machine-actionable Open Science ecosystem aligned with EOSC and FAIR-by-design standards. Know more at https://ostrails.eu/goals.