Street tiles

Wisp draws the streets near you from pre-built tiles. Each tile is a quarter of a degree of latitude and longitude. It holds the streets, paths and water from OpenStreetMap inside that square, and nothing else: no names, no buildings, no addresses.

This is a database derived from OpenStreetMap, so you get it under the same terms we got the original.

• Per tile, exactly as the app fetches it: https://tiles.claphamdigital.com/v1/q4/<row>/<col>.wbm.gz, where row = floor((latitude + 90) × 4), capped at 719 so latitude +90 falls in the last row, and col = floor((longitude + 180) × 4), with the column taken modulo 1440 (so longitude +180 is column 0).
• The index of every published tile: v1/q4/manifest.json. It lists each tile with the SHA-256 of its uncompressed bytes, its sizes, its polyline and vertex counts, and a border flag on tiles at the edge of the covered region.

157,959 tiles covering North America, about 4.1 GB compressed, built on 15 September 2026 from Geofabrik’s North America extract (OpenStreetMap data as of 14 September 2026).

Any HTTP client can download them. Set a User-Agent that names your tool: requests carrying some libraries’ default user agent (Python’s urllib, for example) are refused, and a descriptive one works.

Each file is gzip around a small binary format, little-endian throughout:

HEADER   "WBM1"                                  4 bytes
         minLat, minLon, maxLat, maxLon          Float32 degrees (the tile's box, one Float32 step outward)
         count                                   UInt32, the number of polylines
BODY     count × { kind UInt8 (0 street, 1 water) · n UInt16 (≥ 2) · n × (lat Float32, lon Float32) }

• A polyline whose last vertex equals its first is a closed ring. A ring that crosses a tile edge arrives as open pieces that meet on the edge.
• Geometry is clipped exactly at the tile edge: a street that crosses an edge is split into pieces that share a vertex on it.
• A tile with nothing in it (open water, or land with no mapped streets) is still published, as a header with a count of zero. A missing tile was never built. It does not mean there is nothing there.
• A tile marked border in the manifest lies partly outside the boundary of Geofabrik’s North America extract (north-america.poly) and holds only data from inside that boundary, so it can be incomplete beyond it.
• Coordinates are Float32 degrees, rounded by up to about a metre. That is fine for drawing and unfit for measurement.

• Streets: OSM highway = motorway, motorway_link, trunk, trunk_link, primary, primary_link, secondary, secondary_link, tertiary, tertiary_link, unclassified, residential, living_street, pedestrian, footway, path, steps, cycleway.
• Water: OSM waterway = river, stream, canal, riverbank, plus natural=water and landuse=reservoir|basin ways.
• Ways only. Water mapped as multipolygon relations is not included, so many large lakes are missing.
• Coastlines are not included, so the sea is not drawn.

The method is published too, so the database can be rebuilt from OpenStreetMap. The Geofabrik North America extract is filtered with osmium tags-filter to the ways kept above, node locations are attached with osmium add-locations-to-ways, and build_tiles.py splits every way at tile edges and packs one file per tile.

• BUILD.txt: the exact commands
• build_tiles.py and build_basemap.py: the build scripts

Rebuilding today uses newer OpenStreetMap data and produces different tiles. The published tiles are the reference copy.

The tiles are © OpenStreetMap contributors and are made available under the Open Database License (ODbL) v1.0. Any rights in individual contents of the database are licensed under the Database Contents License.

If you use this database, or anything made from it such as a rendered map, publicly, credit “© OpenStreetMap contributors” and say the data is available under the ODbL. If you change the database and use the changed version publicly, or publicly use something made from the changed version, you must offer that changed database under the ODbL, or offer the changes or the method you used to make it. This is a summary; the licence text governs.

Wisp’s chart is a Produced Work made from this database, and credits OpenStreetMap contributors on the chart. The app downloads the tiles published here, unchanged. The app’s own code and artwork are separate works and are not covered by this licence.

The tiles are provided as is, with no warranty. Streets are simplified and may be out of date or wrong; do not rely on them for navigation or safety.

A tile request names only the tile’s row and column, never your coordinates. What a request reveals, and what the host records, is set out in Wisp’s privacy policy.