KOS-based web services (non-exhaustive list)

SKOS API or SKOS based web services

CATCH Vocabulary and alignment repository demonstrator
http://www.cs.vu.nl/~lourens/STITCH/repository/ (with mapping elements)
and list of related work http://www.cs.vu.nl/STITCH/repository/services.html
EIONET GEMET web services. REST-like
http://www.eionet.europa.eu/gemet/webservices?langcode=en
Explicator Project and vocabulary search web service (XML-RPC)
http://explicator.dcs.gla.ac.uk/
http://explicator.dcs.gla.ac.uk/Vocabularies/suggestionServer.html
HILT SRU/W Server (with mapping elements)
http://hilt4.cdlr.strath.ac.uk/hilt_sru.cgi
Library of Congress Authorities and Vocabularies service (REST)
http://id.loc.gov/authorities/ Linked data
NERC (BODC) Data Grid’s Vocabulary Server SOAP or HTTP-POX
http://vocab.ndg.nerc.ac.uk/ (with mapping elements)
http://www.bodc.ac.uk/products/web_services/vocab/
NBII Biocomplexity thesaurus web services. SOAP
http://nbii-thesaurus.ornl.gov/thesaurus/
OCLC terminology services project and prototype. SRU/CQL
http://www.oclc.org/research/projects/termservices/
ONKI Web service. http://www.yso.fi/
http://www.seco.tkk.fi/publications/2009/tuominen-et-al-onki-skos-2009.pdf
STAR – Semantic Technologies for Archaeological Resources Project. University of Glamorgan. STAR semantic terminology services. SOAP
http://hypermedia.research.glam.ac.uk/kos/STAR/ http://hypermedia.research.glam.ac.uk/kos/terminology_services/
STW – German National Library of Economics REST like web service
http://zbw.eu/beta/stw-ws
SWAD Europe SKOS API. http://www.w3.org/2001/sw/Europe/reports/thes/skosapi.html

Other APIs

ADL Thesaurus Protocol. (2003). http://www.alexandria.ucsb.edu/thesaurus/protocol/
FAO Agrovoc web services
http://aims.fao.org/website/Documentation/sub
Becta Vocabulary Bank Web Services. SRU/Zthes
http://bank.vocman.com/bank-webapp/technical
Getty vocabularies web services. (SOAP and HTTP)
http://www.getty.edu/research/conducting_research/vocabularies/vocab_web_services.pdf

Some background

Binding, C; Tudhope, D. 2004. KOS at your service: Programmatic access to knowledge organization systems. Journal of Digital Information, 4 (4)
http://journals.tdl.org/jodi/article/view/110/109
Tudhope D., Koch T., Heery R. 2006. Terminology Services and Technology: JISC state of the art review
http://www.jisc.ac.uk/media/documents/programmes/capital/terminology_services_and_technology_review_sep_06.pdf