5-star Open Data

Tim Berners-Lee, the inventor of the Web and Linked Data, has created a rating system for data on the web. Each star represents better qualities for the data to be more usable and interoperable.

Open license

First, your data must be openly licensed, so that others can reuse it. This way, you are giving anyone who is interested a permission to re-use the data for their purposes. An openly licensed pdf qualifies for one star, but it’s still hard to reuse.


Machine-readable structured data

Second, you want the data to be readable and organized in a way that a computer can process it. Structured data in a spreadsheet can be sorted, filtered, and visualized.


Open format

Third, you do not want the re-users to have to buy specific software to be able to access the data. That’s why you want to make it available in a non-proprietary open format, for example by using CSV instead of Excel.


Unique identifiers

Things cannot always be identified based on natural language. To be able to distinguish, let’s say Finnish lakes by the name of Pyhäjärvi from one another, you will need to have unique identifiers for them. The fourth star is granted for the use of URIs, Uniform Resource Identifiers, and other open standards from W3C, the World Wide Web Consortium.


Linked Open Data

The fifth star comes from linking your data on the web in a way that it uses data defined elsewhere rather than records the same data over and over again. Linked data does this.