The Protomaps project is the PMTiles format, its tooling, and a 120GB basemap vector cartographic tileset created from OpenStreetMap and other open data sources. PMTiles is not limited to storing vector data - it’s also used for raster data, like scans of historical paper maps. Mapping apps often don’t just need to show vectors of buildings, boundaries and places. Some apps need elevation data, since interesting places on Earth aren’t flat!
