ULDK (land parcel location service) allows for spatial location of parcels, based on their identifiers, using information contained in land and buildings register in counties. The user does not need to know in which county the parcel is located or what is the structure of the database. The ULDK service uses its own list of servers and searches the appropriate county database.
If the parcel is found, then the user receives the geometry in WKB format, which is a well-known GIS standard.

Example of a request for the parcel with the given identifier
https://uldk.gugik.gov.pl/?request=GetParcelById&id=141201_1.0001.1867/2

Description of all available requests: [1]