The Spatial Information Services Stack Vocabulary Service (SISSVoc) is a Linked Data API for accessing published vocabularies. SISSVoc provides a RESTful interface via a set of URI patterns that are aligned with SKOS. These provide a standard web interface for any vocabulary which uses SKOS classes and properties. The SISSVoc implementation provides web pages for human users, and machine-readable resources for client applications (in RDF, JSON, and XML). SISSVoc is implemented using a Linked Data API façade over a SPARQL endpoint. This approach streamlines the configuration of content negotiation, styling, query construction and dispatching. SISSVoc is being used in a number of projects, mainly in the environmental sciences, where controlled vocabularies are used to support cross-domain and interdisciplinary interoperability. SISSVoc simplifies access to vocabularies for end users, and provides a web API to support vocabulary applications.