Getting started

Welcome to Snow Owl! If you're looking at this documentation for the first time, we recommend first reading through the Getting Started with Snow Owl guide to help orient you to the basic features. Once you're familiar with the lay of the land, this User Guide can help answer more detailed or advanced questions that you have.

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What is Snow Owl?

Snow Owl is an authoring platform for clinical terminologies. It supports the extended SNOMED CT compositional grammar (ESCG) for semantic querying, and allows the creation of intensional and extensional subsets among other reference set types that follow the IHTSDO SNOMED CT RF2 specifications. In addition to authoring SNOMED CT or a national extension, Snow Owl is designed to support a variety of ontologies and classifications. Snow Owl is designed to be a framework to support higher-level terminology authoring tools, such as drug and device dictionaries.

Snow Owl is built upon the Eclipse platform, which allows us to easily integrate Eclipse-based application architectures within a single tool. An example of this integration is Stanford's Protégé Ontology Editor, which allows us to use any Protégé-compatible description logic classifier. Snow Owl also seamlessly integrates with information model tooling, such as the HL7 Static Model Designer and our Logical Information Model tooling to support domain model design, ontology authoring, and the binding between the two.

Snow Owl can operate in two modes; in stand-alone mode supporting a single user or in collaborative mode with multiple users connected to a single server authoring the same terminology simultaneously in a distributed fashion.

Key features include:

For an introduction to the main functions and features please read the Getting Started with Snow Owl guide.

How can I run it?

System requirements


Disk space requirements vary depending on the number and types of terminologies installed. For example, the complete history of SNOMED CT (including over a decade's worth of detailed changes), with ICD-10, ICD-10-AM, and ATC takes about 12GB.

Collaborative environment

Launching the application for the first time

Unzip the Snow Owl file, open the Snow Owl folder, and double-click on the SnowOwl application icon .

Opening the application

Click Next on the Welcome to Snow Owl page to proceed.

Welcome to Snow Owl

Enter your username and licence code. You can use the Verify licence button to check if your code is valid. Click Next to proceed.

Entering user name and licence code

Provide a password that you want to use for logging in, and re-enter your password. Click Next to proceed.

Entering a password for login

Verify that you agree with the End User licence agreement. Click Next to proceed.

End user licence agreement

Verify that you agree with the terms of the IHTSDO licence agreement. Click Accept to proceed.

IHTSDO licence agreement

Click OK on the login screen to start the application. You can save your password by checking Remember me. If you are working in a collaborative mode, you need to click on the Repository... button and specify the terminology server before starting the application.

Login screen

Launching the application

Login screen

Note: If you are launching Snow Owl for the first time, please follow the steps described in the section above.

Embedded and remote repositories

Depending on what type of repository you choose at startup, Snow Owl can operate in either standalone or collaborative mode. By default it starts up as a standalone application and uses an embedded repository. You can review and change this setting by clicking on the Repository... button on the login screen.

Terminology repository settings

Integrate with LDAP

Snow Owl is capable of using an LDAP directory for user authentication and authorization. The Snow Owl Server already includes an embedded, pre-configured LDAP server instance ( Apache Directory), which is populated with the following initial entries:

Logged in with all user roles

Additional users can be created and assigned to groups using the Apache Directory Studio application.

What version of SNOMED CT is included?

All of them! Snow Owl includes all versions of SNOMED CT since the January 31, 2002 release. To see the most recent release available in Snow Owl, double-click on SNOMED CT Concept in the SNOMED CT view. You can find the view on the left side of your screen.


Detailed information about SNOMED CT will be displayed in the editor, which is located in the middle of your screen. A synonym specifies the current version, which is (as of Snow Owl 3.5) SNOMED Clinical Terms version: 20140131 (January 2014 Release).

Concept editor displaying the SNOMED CT concept

To switch to an older version, click the icon in the toolbar. You can see a list of the terminologies and local code systems that are supported in Snow Owl. The version selector always shows the version that is currently used in Snow Owl. By default, the latest version is used, which is indicated with MAIN. If you are using an older version, you will see the release date (for SNOMED CT), or the version number (e.g. for Local code systems).

To work with an earlier version version,

Selecting a SNOMED CT release

For for further information please refer to the chapter Versioning.