Organizations, and especially public sector institutions, collect a large amount of data within their competences. Much of the data can be published or "opened" in open data format. Open data guidelines need to define all data sets that should be published by municipalities in the form of open data. Therefore, the purpose of comparative analysis is, in addition to the established needs of citizens for data and information, to propose how certain best practices can be applied at European level in relation to certain data sets, the way they are published, or the way which is generally approached in the country's open data policy.