OpenStreetMap

OpenStreetMap is a database of roads, buildings, paths, shops and boundaries that contributors add and correct, often from satellite imagery and GPS traces. The data is published under the Open Database License (ODbL): use it for anything, commercial work included, as long as maps credit '© OpenStreetMap contributors' and any modified version of the database you make public stays under the same licence. Mapbox, MapTiler and many other services build their maps from it.

The OpenStreetMap Foundation runs public tile servers and the Nominatim geocoder, but they are funded by donations and meant for light use: the usage policies require attribution, forbid bulk downloading and allow heavy users to be blocked without notice, and Nominatim allows at most one request a second. Apps with real traffic should use a tile provider built on OSM data or host their own tiles, for example with OpenMapTiles or PMTiles.