The Open Semantic Framework (OSF) Web services provide a uniform and platform-independent means for accessing and exposing all of the semantic technology capabilities of OSF via structured RDF (Resource Description Framework) data. The central organizing perspective of these services is that of the dataset. These datasets contain instance records, with the structural relationships amongst the data and their attributes and concepts defined via ontologies (schema with accompanying vocabularies).

The OSF Web services are generally RESTful in design and are based on HTTP and Web protocols and open standards. There are presently 27 Web services in the framework covering functionality in CRUD, revisioning, search, tagging, ontology management, and export and import. All Web services are exposed via APIs and SPARQL endpoints. Each request to an individual Web service returns an HTTP status and optionally a document of resultsets. Each results document can be serialized in many ways, and may be expressed as either RDF, pure XML, JSON, or different flavors of irON.

The OSF Web services have direct interfaces to the underlying engines used by OSF, including the Virtuoso RDF triple store (via ODBC and HTTP), the Solr faceted, full-text search engine (via HTTP), the OWLAPI and the Gate NLP framework. However, the OSF Web Services have been designed to be fully platform-independent. Their design also allows other specialized systems to be included, such as analysis or advanced inference engines.

The OSF Web services are open source (Apache 2 license) and designed for extensibility. The OSF Web services and their extensions and enhancements are fully documented on the OSF wiki.