Institute's service:

XXX

Futher services:

General:

• http://www.geonames.org/export/web-services.html
• http://nominatim.openstreetmap.org/
• gnd ortsnamen

Historical:

• https://www.getty.edu/research/tools/vocabularies/tgn/
• http://pelagios.dme.ait.ac.at/api