The lightning data (lightningdata) API service contains lightning data from stations located in Denmark. You can read more about lightning data and how they are attained under data information.
If you want to download large quantities of historical lightning data, we recommend that you use DMI’s bulk download service. The service lets you download .zip files, each containing historic data for a month going back to 2002. You can also download all historic data by selecting the file all.zip.