# Routing overview

> geolith Routing is in development and not deployed for public use: a Rust router with a Valhalla-compatible API (route, isochrone, matrix, map matching) that answers from the routing part of a .glx file geolith builds, read in HTTP ranges. What it is, how it works, and its status.

::warning
**Status: in development. Not deployed for public use.** There is no routing endpoint on geolith.app or api.geolith.app, no hosted API and no pricing. The router and geolith's routing builder both work: on Berlin, routes on geolith-built tiles are byte-identical to Valhalla 3.9.1. A test Worker on workers.dev answers routes, but too slowly to offer yet. Until routing launches, the hosted platform offers [geocoding](/search) and [vector tiles](/tiles) (India tile set today; planet tiles in development) only. See [Status and roadmap](/routing/status).
::

geolith Routing turns OpenStreetMap into a road graph and answers routing requests from it. The [geolith builder](/builder) writes the graph as the routing part of a `.glx` file. A router, written in Rust, reads that part in byte ranges and answers six endpoints with Valhalla-compatible request and response bodies: `/route`, `/isochrone`, `/sources-to-targets`, `/trace-route`, `/trace-attributes` and `/status`. A Valhalla client changes only the URL.

## How it works

```text
OpenStreetMap .osm.pbf
        │
        ▼
geolith builder (Rust)
  tag rules → parse → edges → access → turn restrictions
  → enhance → hierarchy → shortcuts
  → graph tiles on three grids (4°, 1°, 0.25°)
        │
        ▼
.glx file
  file header (256 bytes) → routing part:
  routing header · tile index · zstd dictionary
  · tiles, each a block directory + 64 KiB zstd blocks
        │  HTTP range requests for the blocks a request touches
        ▼
router (Rust, built to WebAssembly, in a Cloudflare Worker)
  snap locations → search the road hierarchy → build the answer
        │
        ▼
Valhalla-compatible JSON
```

- **One file, no database.** The router keeps the tile index in memory and fetches only the 64 KiB blocks of the tiles a request touches. The file can sit in R2 or on local disk.
- **Separate from search.** A `.glx` file holds parts: `SRCH` for search, `ROUT` for routing. Search and routing are planned as two hosted files, so they update independently. See [The routing part](/routing/routing-part).
- **Edge only, no servers.** The router library (`geolith-router`) is pure Rust and does no I/O of its own: it asks for the bytes it needs and the program around it fetches them. The same code runs as WebAssembly in a Cloudflare Worker reading from R2. See [Self-hosting](/routing/self-hosting).

## Pages

- [How it works](/routing/how-it-works): from OpenStreetMap to a response, step by step, and where each piece of data lives.
- [The routing part](/routing/routing-part): the byte layout of the routing part of a `.glx` file and how a reader reads it.
- [API](/routing/api): the six Valhalla-compatible endpoints, with one example each. Not callable yet.
- [Self-hosting](/routing/self-hosting): the router library, the Worker app, and the latency measured on the edge.
- [Traffic and live data](/routing/traffic): historical speeds in the routing part, and live speeds and closures supplied by the caller.
- [Status and roadmap](/routing/status): what is done, what is in progress, what is next, and the accuracy tables.

## Credit

geolith's routing builder, graph tile format and router are ported from [Valhalla](https://github.com/valhalla/valhalla) 3.9.1, released under the MIT license. The graph tiles in a `.glx` routing part are byte strings in that tile format, and the request and response bodies follow Valhalla's API.