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Welcome to the Finnish Ontology Library Service ONKI!

The ONKI service contains Finnish and international ontologies, vocabularies and thesauri needed for publishing your content cost-efficiently on the Semantic Web. Ontologies are conceptual models identifying the concepts of a domain. They contain machine "understandable" descriptions of the relations between the concepts.

ONKI is published and maintained by Semantic Computing Research Group SeCo. It is part of the on-going project to build a national semantic web infrastructure to Finland (FinnONTO).

Ontologies and vocabularies

Browse and search all available ontologies and vocabularies with this online user interface. The ontologies and vocabularies are listed on the front page of this service.

You can also access any of the available ontologies or vocabularies with the developer APIs listed below.

Executive Summary

ONKI helps you to link your data globally, making it compatible with the semantic web. Check following links:

Use the ONKI Browser to check what ontologies are already available. Check below for tools and services ONKI provide for your applications.

What is ONKI? (in Finnish)

For Ontology and Thesaurus Owners

Share your ontologies and thesauri to others at ONKI:

For Developers

Application interfaces and software components are provided for application developers as shown below. To use the APIs and components, please sign up first!

Video instructions

See video instructions for integrating ONKI into your system (in Finnish).

ONKI Living Lab at your service!

The ONKI is provided as a part of the ONKI Living Lab - an open lab for testing the latest semantic web technologies in practice, with real users like you. Currently, over 10 000 people are using ONKI each month.

We hope you like the ONKI service and enjoy using it for your purposes!

If you encounter any problems or have improvement ideas, please contact the ONKI team. We are also very much interested in your success stories in using ONKI - please share your experiences!

The ONKI Team

How can we help you?

Contact us at: We are located at the Aalto University.

ONKI Living Lab is a project of the Semantic Computing Research Group (SeCo).

Former members: Kim Viljanen, Rami Alatalo.


Email us at

To give ontology specific feedback, go to ONKI Browser, click on Feedback and select the ontology.

Join the ONKI mailing list

Join the ONKI mailing list to get information about major changes and news regarding ONKI. The list is moderated and amount of traffic is low (typically at most only a few messages per month).

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