Open APIs
Geoserver
Hosts various geospatial datasets: implements WMS and WFS
API location: https://kartta.hel.fi/ws/geoserver/avoindata/
GeoServer is a Java-based software server that allows users to view and edit geospatial data. Using open standards set forth by the Open Geospatial Consortium (OGC), GeoServer allows for great flexibility in map creation and data sharing.