Snow Owl Docs


Snow Owl® is a highly scalable terminology server with revision-control capabilities and collaborative authoring platform features. It allows you to store, search, and author high volumes of terminology artifacts quickly and efficiently.
Generic core functionality and SNOMED CT tooling are open-source, all other features require a license.
If you’d like to see Snow Owl in action, the
Snowray Terminology Service™ provides a managed terminology server and high-quality terminology content management from your web browser.

Example use cases

  • You work in the healthcare industry and are interested in using a terminology server for browsing, accessing, and distributing components of various terminologies and classifications to third-party consumers. In this case, you can use Snow Owl to load the necessary terminologies and access them via FHIR and proprietary APIs.
  • You are responsible for maintaining and publishing new versions of a particular terminology. In this case, you can use Snow Owl to access collaboratively and author the terminology content and at the end of your release schedule publish it with confidence and zero errors.
  • You have an Electronic Health Record system and would like to capture, maintain, and query clinical information in a structured and standardized manner. Your Snow Owl terminology server can integrate with your EHR server via standard APIs to provide the necessary access for both terminology binding and data processing and analytics.


Revision-controlled authoring

  • Maintains multiple versions (including unpublished and published) for each terminology artifact and provides APIs to access them all
  • Independent work branches offer work-in-progress isolation, external business workflow integration, and team collaboration

SNOMED CT and others

  • SNOMED CT terminology support
  • With its modular design, the server can maintain multiple terminologies (including local codes, mapping sets, and value sets)

Various sets of APIs

Highly extensible and configurable

  • Simple to use plug-in system makes it easy to develop and add new terminology tooling/API or any other functionality

Full-text search and data storage

  • Built on top of
    Elasticsearch (highly scalable, distributed, open source search engine)
    • Connect to your existing cluster or use the embedded instance (supports up to Elasticsearch 8.x)
    • All the power of Elasticsearch is available (monitoring, analytics, and many more)


In March 2015,
SNOMED International generously licensed the Snow Owl Terminology Server components supporting SNOMED CT. They subsequently made the licensed code available to their members and the global community under an open-source license.
In March 2017,
NHS Digital licensed the Snow Owl Terminology Server to support the mandatory adoption of SNOMED CT throughout all care settings in the United Kingdom by April 2020. In addition to driving the UK’s clinical terminology efforts by providing a platform to author national clinical codes, Snow Owl will support the maintenance and improvement of the dm+d drug extension which alone is used in over 156 million electronic prescriptions per month. Improvements to the terminology server under this agreement were made available to the global community.
Numerous other organizations have directly or indirectly contributed to Snow Owl, including:
  • Singapore Ministry of Health
  • American Dental Association
  • University of Nebraska Medical Center (USA)
  • Federal Public Service of Public Health (Belgium)
  • Danish Health Data Authority
  • Health and Welfare Information Systems Centre (Estonia)
  • Department of Health (Ireland)
  • New Zealand Ministry of Health
  • Norwegian Directorate of eHealth
  • Integrated Health Information Systems (Singapore)
  • National Board of Health and Welfare (Sweden)
  • eHealth Suisse (Switzerland)
  • National Library of Medicine (USA)
Last modified 1mo ago