© Crown copyright and database rights 2025 Ordnance Survey 0100031673

OS Maps API serves pre-rendered raster tiles and contains OS MasterMap Topography Layer, 1:25 000 Scale Colour Raster, OS Zoomstack and more. This is a ‘transactional’ web service which includes data licensing.

Maps are requested using the Open Geospatial Consortium Web Map Tile Service (OGC-WMTS) standard or RESTful ZXY.  OS Maps API is available in two projections; British National Grid for GB data and the global coordinate system, Web Mercator. And there are four styles available: Road, Outdoor, Light (EPSG: 27700 and 3857) and Leisure (EPSG: 27700), each map style contains OS OpenData and Premium data layers.

OS Maps API is charged per 'transaction' where one 'transaction' is deemed to serve 15 raster tiles sized 256 pixels by 256 pixels (983,040 pixels).