This talk will present strategies and python tools to create semantically interoperable REST APIs. After the problem statement, various solutions will be presented, including: * contract-first api development with OpenAPI 3, ontologies and controlled vocabularies like the ones published by the European Union (https://op.europa.eu/en/web/eu-vocabularies/authority-tables); * the rdflib and pyld python libraries for processing json-ld and RDF files (https://en.wikipedia.org/wiki/Resource_Description_Framework); * the use of centralized catalogs such as schema.org. Prerequisites: * no prior knowledge of semantics and ontologies; * practical experience with OpenAPI, json schema and data modeling and API design in general.