GDPR's Right to Data Portability requires data to be provided in an interoperable, commonly used, and machine-readable format and facilitates its transfer between controllers. However, a major challenge for such data to be used between different services is agreement over common schemas to define the semantics of data. We present our vision of a holistic process for organisations to export and import data in an interoperable manner by using ontology matching and mapping techniques to identify a common model towards schema-negotiation. Our approach enables organisations to exchange data using a common base schema, thereby motivating greater innovation in the ecosystem through data reuse. To demonstrate our vision, we present a proof-of-concept application of ingesting data from Facebook into Twitter.