German postcode-to-federal-state mapping: OpenPLZ API / OpenStreetMap contributors.
Source: https://github.com/openpotato/openplzapi.data
Export: https://raw.githubusercontent.com/openpotato/openplzapi.data/main/src/de/osm/streets.updated.csv
Retrieved: 2026-11-02
License: Open Database License (ODbL) 1.0
https://opendatacommons.org/licenses/odbl/1-0/

DLC modification: deduplicated postcode/locality/regional-key combinations;
the first two digits of the official municipality key map to federal states.
Cross-state postcodes retain locality distinctions rather than guessing a state.
The derived database is available at /data/postal-regions-de.json under ODbL 1.0.
No external lookup service is called by the website for this mapping.