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The NCTS APIs are used to authenticate to the service, query and manipulate terminology resources, and syndicate files.

NCTS Authentication API

This allows a client to request an access token. The token can then interact with secure API endpoints.

Note that authentication is not required for the capability statement and syndication feed.


This is a profile of the Atom Publishing Protocol. It allows interrogation of a feed of terminology content. It also provides links to download the content.

NCTS FHIR (Integration) API

This is a profile of the FHIR REST API and Terminology Service API. The NCTS uses two main types of FHIR APIs:

  • An API specification that defines the operations and behaviour of a FHIR server. This includes search, create, read, update and delete operations for interacting with any type of resource, in the REST architectural style.
  • A Terminology Service API for interacting with FHIR terminology servers. This API includes operations specific to servers hosting SNOMED CT and LOINC terminology content.

Typical operations performed by the service

Creation, Reading, Updating, Deleting, and Searching for NCTS FHIR resources: standard life cycle operations to manage NCTS FHIR Code System, Value Set, and Concept Map resources.

Value Set expansion: obtain an on-demand list of codes and associated descriptions based on a stored Value Set with support for filtering.

Concept Lookup: obtain information about a code or coding system.

Value Set based validation: validate one or more codes against a stored Value Set.

Concept translation: translating a source concept to a target concept based on a stored Concept Map.

Technical guidance

NCTS Guide for Implementers

NCTS Specifications