The key danish dataportals are
Geodata-info.dk
This is on of the two main meta sites for national data it differs form the other (datavejviseren.dk) in that it only contain spatial data it also uses the inspire tagging system (see https://knowledge-base.inspire.ec.europa.eu/tools/inspire-themes_en). geodata-info.dk is a pure metadata server and contains nu data as such just a searchable data descriptions with links to where the data can be obtained.
Datavejviser.dk
This is the other of the two main meta sites for national data it differs form the other (Geodata-info.dk) in that it contain both spatial data and non spatial data. You can also search by thee own tag system and by the organisation responsible for the data.
Dataforsyning.dk
Dataforsyningen is the main website for locating and retrieving data create by “Klimadata styrelsen” which includes most most danish infrastructural data. To download data or acces the data as webservices you need to create a user and a token (see this guide). Dataforsyningen also has a QGIS plugin that can acces the data as webservides.