This tool uses OpenStreetMap data for the buildings and base layer. Unfortunately, it kind of hides that it is doing that, which sucks. Usually the required at

This tool uses OpenStreetMap data for the buildings and base layer. Unfortunately, it kind of hides that it is doing that, which sucks. Usually the required attribution is placed in a corner of the map. Shade Map has a little information-i there which does appear to list OpenStreetMap according to my browser's dev-tools, but it seems to be broken and gets hidden behind other page elements, so only '© Shade Map |' is visible.