API Libraries

We have extensive practical experience in developing applications on top of linked data.  We’ve found that doing this with a well developed access layer (Application Programming Interface, or API layer) has helped produce effective, adaptable and well respected applications.

We have evolved the API libraries and frameworks that we use to deliver our projects.

For more information and queries about licensing our API library technologies please contact us: api-info@epimorphics.com


SAPI-NT is the next generation of our Streaming API library, for creating APIs over RDF data. This includes a flexible Kotlin library and starter application for providing flexible REST APIs over published Linked Data. It allows data to be accessed in JSON and CSV, as well as linked-data formats, making it easy for non-linked-data experts to work with the published data. As a streaming API it allows arbitrary scales of data to be returned from a query and includes a batch option to allow queues of large queries to safely managed. SAPI-NT supports making multiple data sources accessible from a single API, including support for non-triple store backends (e.g. Cassandra).

Our API library includes automated API documentation generation including an implementation of the OpenAPI documentation standard (previously Swagger).

We have licensed our earlier generation technology, SAPI, to service providers building and running high volume linked data services.

We are actively developing and enhancing SAPI-NT and our API library stack.


Epimorphics Linked Data API (Elda) is our implementation, in Java, of the Linked Data API specification.  Elda has been widely used on many linked data implementations globally.

Elda provides a configurable way to create an API to access RDF data using simple RESTful URLs. These URLs are translated into queries to a SPARQL endpoint. The API developer writes an API spec – in RDF – which specifies how to translate URLs into queries.

We’ve learned a lot of lessons from using and supporting Elda, and it still powers a number of key public services, but we’re not actively promoting its use in new projects.

Elda is open source licenced and documentation can be found here: