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SKILL.md
npx skills add maplibre/maplibre-agent-skills --skill maplibre-pmtiles-patterns
Serverless vector and raster tiles with PMTiles for MapLibre GL JS — single-file format, HTTP range requests, hosting on S3/R2/GitHub Pages, generating with Planetiler or tippecanoe, and the pmtiles protocol. Use when you need no tile server or want to host tiles from static storage.
npx skills add maplibre/maplibre-agent-skills --skill maplibre-pmtiles-patterns
PMTiles is a single-file format for vector or raster map tiles. You host one (or a few) files on any static host; MapLibre requests byte ranges over HTTP. No tile server, no dynamic backend. This skill covers when to use PMTiles, how to generate and host them, and how to connect them to MapLibre GL JS.
type: 'vector', type: 'raster', or type: 'raster-dem' accordingly..pmtiles file typically contains the full tile pyramid (all zoom levels) and all layers (vector or raster) in one archive. The format stores tiles in a compact layout (e.g. Hilbert curve) so the client can request only the byte ranges it needs. For very large coverage you may split by region into multiple files.Range headers works.When to prefer PMTiles over a traditional tile server:
When to prefer a tile server (e.g. tileserver-gl, Martin):
MapLibre does not speak PMTiles natively. You use the PMTiles library to add a protocol handler so that a pmtiles:// (or https:// to a .pmtiles file) source works.
Install:
Register the protocol and use in a style:
addProtocol changed in MapLibre GL JS 4.0.0. The v3 (params, callback) signature is gone — the 4.0.0 changelog entry reads "Changes addProtocol to be promise-based without the usage of callbacks and cancelable". A handler is now async (params, abortController) and must resolve to an object with a data property: {data, cacheControl?, expires?}. Resolving to a bare ArrayBuffer, Blob, Response or Uint8Array is not the contract — MapLibre reads .data off whatever the handler resolves with, so a bare buffer reads as no data at all and an arrayBuffer request is filled with an empty ArrayBuffer(0): the tile comes back blank instead of erroring. Register the handler on the module — maplibregl.addProtocol(...), or the named addProtocol import — once, before the first map is constructed: the protocol registry is global, so one registration covers every map on the page.
PMTiles users need no code change. new pmtiles.Protocol().tile is the library's v4 handler wrapped in its v3compat shim (pmtiles ≥ 3.0.0): it checks whether the second argument is an AbortController and adapts, so the single line maplibregl.addProtocol('pmtiles', protocol.tile) is correct on GL JS v3, v4, v5 and v6, and it already resolves to {data: Uint8Array, cacheControl, expires}. A project still on pmtiles 2.x has a callback-only tile and must upgrade the library along with MapLibre. The contract above is what you need when you write your own handler, or when a hand-rolled callback handler broke on the v4 upgrade.
Referencing layers: The style has one source (e.g. sources.tiles) pointing at the .pmtiles URL. Each layer in the layers array that draws from that file uses source: 'tiles' and "source-layer": "layerName", where layerName is the name of a vector layer inside the file (from whatever schema the tiles use). Add multiple style layers with different source-layer values to show roads, labels, etc. from the same file.
Important: The url can be pmtiles://https://... (protocol + HTTPS URL to the .pmtiles file). The library will fetch the file via range requests. Your style must still define glyphs and sprite if you use labels or icons (see maplibre-source-wiring).
Zoom range comes from the header — use url:, not tiles:. A PMTiles archive stores its own min/max zoom in the header. When you reference it with url: 'pmtiles://https://...', the protocol reads that header and hands MapLibre a TileJSON with the correct minzoom/maxzoom, so overzoom past the archive's max works automatically and you never set maxzoom by hand. If you instead hand-wire a tiles: ['pmtiles://.../{z}/{x}/{y}'] template, you bypass that header lookup. The protocol still serves the per-tile requests up to the archive's max — this is not a missing-handler or 404 problem — but MapLibre, given no zoom range, assumes maxzoom: 22 and keeps requesting zoom levels the archive doesn't contain, which come back empty (blank tiles for vector, nothing for raster) instead of overzooming. Always use url:.
❌ A source has exactly two tile-location properties: url and tiles. There is no tileset property in the MapLibre style spec, for vector, raster or raster-dem sources. If a zoom range is wrong, fix which of the two you used; don't reach for a third.
Raster and raster-dem: The same protocol works for raster PMTiles. Use a type: 'raster' source for imagery. For terrain/elevation, use a type: 'raster-dem' source with "encoding": "terrarium" (or "mapbox") so MapLibre can apply hillshade or 3D terrain; then reference it in the style’s terrain property. Example source:
Using PMTiles with React: Register the protocol once at application startup, not inside each component, so MapLibre has the handler before any map mounts. For example, call maplibregl.addProtocol('pmtiles', protocol.tile) in a root-level effect or when your map provider initializes. On unmount of the last map (or when the app tears down), call maplibregl.removeProtocol('pmtiles') to avoid leaks. See PMTiles for MapLibre GL (Protomaps) for a React-oriented setup.
Any host that serves the file and supports HTTP Range requests is suitable.
Cache-Control and optionally use CloudFront.Accept-Ranges: bytes and responds correctly to Range headers.CORS: Browsers will send cross-origin requests to the PMTiles URL. The host must send Access-Control-Allow-Origin: * (or your domain) and Access-Control-Allow-Headers: Range (or allow all). Otherwise MapLibre will fail to load tiles.
Cache headers: For better performance, set long cache for the .pmtiles file (e.g. Cache-Control: public, max-age=31536000 if the file is immutable). CDNs will cache range responses.
The pmtiles CLI is the official command-line tool for working with PMTiles (and MBTiles for conversion). It’s a single binary with no runtime dependencies—you download it and run it.
Why install and use it:
pmtiles convert in.mbtiles out.pmtiles. This is often the simplest way to get PMTiles when your pipeline already produces MBTiles.pmtiles show <file> prints header and metadata (bounds, zoom range, tile count). pmtiles verify <file> checks archive integrity. Useful for debugging or confirming a file before uploading.pmtiles extract creates a smaller .pmtiles file from an existing one (e.g. by bounding box or zoom range), so you can ship a region or a limited zoom band without regenerating from source.❌ The subcommand list is closed — don't reach for a plausible-sounding verb. go-pmtiles ships exactly show, tile, verify, extract, merge, serve, convert, cluster, upload, edit and version. There is no info verb and no inspect verb, and nothing sets metadata from the command line except edit. To read an archive's header, bounds and zoom range, the command is pmtiles show; to check integrity, pmtiles verify.
Install: Download the binary for your OS/arch from GitHub Releases (go-pmtiles), or use Docker: protomaps/go-pmtiles.
What it does not do: The CLI only works with tile archives (MBTiles and PMTiles). It does not read GeoJSON, Shapefile, OSM, or other source formats. To create PMTiles from those, use a tool that generates tiles (see Generating PMTiles below) and, if that tool outputs MBTiles, run pmtiles convert to get PMTiles.
Two paths: (1) Convert — The PMTiles CLI converts MBTiles ↔ PMTiles only; it does not read GeoJSON, Shapefile, OSM, or other source formats. (2) Generate from source data — Tools like tippecanoe, Planetiler and ogr2ogr via GDAL read from many file types or databases and produce vector tiles (PMTiles or MBTiles). If they output MBTiles, use pmtiles convert to get PMTiles.
See The PMTiles CLI above for why to install it and other commands (show, verify, extract). To convert MBTiles to PMTiles:
The following tools generate tiles from source data (GeoJSON, OSM, Shapefile, PostGIS, etc.). They output PMTiles or MBTiles; if MBTiles, run pmtiles convert to get PMTiles.
Planetiler reads OpenStreetMap (or other sources) and outputs PMTiles or MBTiles in the OpenMapTiles schema.
See Planetiler docs for area names, custom sources, and schema options. Output is a single .pmtiles file you can upload to S3/R2/static host.
tippecanoe generates vector tiles from source formats: GeoJSON, FlatGeobuf, CSV. From v2.17 onward it can output PMTiles directly (-o output.pmtiles). You can also output MBTiles and convert with pmtiles convert.
GDAL’s ogr2ogr generates tiles from many geospatial formats (Shapefile, PostGIS, GeoJSON, etc.) and can write MBTiles or PMTiles (GDAL 3.8+). Best for smaller datasets; tippecanoe is more efficient for large vector tile sets.
PMTiles supports raster tiles (PNG/JPEG, e.g. satellite or pre-rendered imagery) and raster-dem (elevation/terrain, e.g. Terrarium or Mapbox encoding). Use tools that produce raster or raster-dem PMTiles; the same protocol and hosting apply. In the style use type: 'raster' for imagery or type: 'raster-dem' with "encoding": "terrarium" (or "mapbox") for terrain—see MapLibre Integration above for an example.
Overture Maps publishes global open map data. Some providers distribute Overture-derived data as PMTiles (e.g. for buildings, places, transportation). You can also build PMTiles from Overture data with Planetiler or other pipelines. Use the PMTiles URL in your MapLibre style as above.
source-layer, glyphs and sprite, CORS.addProtocol (MapLibre GL JS API) — The custom-protocol handler signature and the {data} return shape.convert, show, verify, extract)This skill is a snapshot. Where a primary source contradicts it — the References above, MapLibre's current documentation, or what MapLibre does when you run it — that source wins. Follow it, then report the disagreement, citing the source and your MapLibre version: editing your installed copy helps no one else and is overwritten on the next update.
// ❌ v3 — on v4+ the second argument is an AbortController, so callback(...) throws,
// and the returned {cancel} has no data: the tile comes back blank
maplibregl.addProtocol('custom', (params, callback) => {
fetch(params.url)
.then((r) => r.arrayBuffer())
.then((buffer) => callback(null, buffer))
.catch((error) => callback(error));
return { cancel: () => {} };
});
// ✅ v4+ — async (params, abortController) resolving to {data}
maplibregl.addProtocol('custom', async (params, abortController) => {
const response = await fetch(params.url, { signal: abortController.signal });
if (!response.ok) throw new Error(`Tile fetch error: ${response.statusText}`);
const buffer = await response.arrayBuffer();
return { data: buffer }; // the {data} wrapper is required; a bare buffer is not
});"elevation": {
"type": "raster-dem",
"url": "pmtiles://https://example.com/elevation.pmtiles",
"encoding": "terrarium"
}pmtiles convert input.mbtiles output.pmtiles# Example: build a PMTiles file for a region (e.g. from a .osm.pbf download)
java -jar planetiler.jar --area=monaco --output=monaco.pmtiles# Direct PMTiles output (v2.17+)
tippecanoe -zg -o output.pmtiles input.geojson
# Or MBTiles then convert: tippecanoe -o output.mbtiles -z 14 input.geojson && pmtiles convert output.mbtiles output.pmtiles