Licensing Open Data

Unlocking data means choosing the right license.

Unlocking data means choosing the right license.

Everything you wanted to know but were afraid to ask.

Making data open and available is not just about choosing a format or having an API. A poor choice in your license can prevent people from using them. A traditional open license reassures potential users that their work on the data will be useful in the long run. So, what license should you pick for your data to be broadly used? There are a few things to consider.

Choosing a license for your open data can usually be one of the biggest challenges for an open data project. There are plenty of licenses available for your data. Choosing one mostly depends on the usage and reach you want to give to your project.

Choose a License Based on National, International and local statutes in Addition to  Reuse

It should be noted that different parts of the world use data licensing terms differently. In the US, works in the “public domain” are works are not covered by intellectual property rights, such as copyright. The copyright might also have expired. The use of the word “public domain” on US Government Publications does not mean the data is completely without restrictions. For example The U.S. government work designation does not apply to works of U.S. state and local governments. Works of state and local governments may be protected by copyright. Data within US Government data sets may also contain third party data which is not a part of public domain.

In Europe, Public Domain has a dual meaning: a work available to the public; a licensing vehicle determining rights of use. In terms of licensing, both the Open Data Institute and the Open Knowledge International define Public Domain as “without rights”.

It is important to note where the data will be released in terms of laws and definitions used within those laws. Next we will see that while we have three choices of licensing, only the first two actually match the Open Definition.

There are Three Options but only Two Meet the Open Definition Standard

Questions about Open Data Licensing can seem complex and certainly are debatable. From an Open Definition point of view there are three options. Two license options and one option to suggest your own license using the Open License by Attribution Option. For practicality, using one of the first two types of licensing works best. Licensing something with your own attributions requires some legal discussions and often have unintended consequences. The Open Data Institute recommends two basic options of licensing open data and includes a Crown License which is similar to the US Public Domain License.



Potential re-users of the dataset are confident that they can use the data in any way (e.g. commercial purpose). An open license will ensure a broader usage of the data and the most diverse audience possible. Remember that the term “public domain” has different implications in Europe than in the US. The Open License can require an attribution at most if it is to meet the Open Definition of Open Data. Anything CC, such as CC0, CC-by is supported by an idea called Creative Commons. Creative Commons is not a legal framework in the way that national copyright laws are legal frameworks. They are, however, agreed upon conventions internationally recognized as valid.


Open License/Licence ouverte, Public Domain, Public Domain/CC0, CC- by, Open Data Commons Public Domain Dedication and License, Open Data Commons Attribution License


Location of theaters on the territory of the City of Brussels



Potential re-users of the dataset will have to play the game by the same rules, which means applying the same license to the reuses. Free licenses will ensure that nobody benefits from the work of others without contributing too. In the case of any license involving Creative Commons, there may be some restrictions on commercial use and other uses CC0 also is called Public Domain which we have discussed earlier as a potential issue in the US. However, the use of CC0 has stood the test of time as a valid license in the US and can be argued to be one of the true “free” licenses on the list below. Please check the footnotes for a complete definition of rights granted by the seven most commonly used CC variants.


ODbL, OSM, CC-by-nd, CC-by,nc-nd, CC-by-nc, CC-by-nc-sa, CC-by-sa




We use the word “extreme” because there is some debate over whether an organization can create their own license and still call the data “Open Data”. The Open Data Institute recommends not creating one’s own license for reasons stated above. However, The Open Knowledge International does claim that making a unique license is possible as long as it follows the tenets of the Open Definition. Potential re-users of the dataset will have to read, understand and be sure that the license allows them to use the data according to their plan. Defining an original license is restraining usage by design and should be considered carefully.


SNCF, SBB etc…


Loudspeaker messages played in Zurich’s rail station