osrm

OSRM, or Open Source Routing Machine, is a high-performance routing engine for road networks designed to run on private servers. It processes OpenStreetMap data to provide fast shortest-path queries for multiple travel modes, notably car, bicycle, and foot. OSRM is open-source and aims to offer offline, low-latency routing suitable for large-scale deployments.

The architecture of OSRM combines preprocessing tools and a server. Data is prepared from OpenStreetMap using osrm-extract to create a routing graph and osrm-contract to apply contraction hierarchies, which dramatically speeds up queries. The server component, osrm-routed, serves HTTP API requests. Travel profiles, written in Lua, define speeds, access rules, and restrictions for each mode, enabling tailored weighting of routes. The resulting graph is stored locally and queried efficiently, allowing rapid responses even on continental road networks.

OSRM exposes a REST-like HTTP API with endpoints for route, table (distance matrix), trip (multi-stop optimization), matchings (map matching), and nearest (snap to roads). Typical responses include distance, duration, and route geometry, with options to request alternatives, step-by-step directions, and various geometry formats. While primarily static, OSRM can incorporate updated local data by re-running preprocessing on new OSM extracts.

Deployment and usage: OSRM runs on commodity servers and is intended for offline use with locally hosted data. Regular updates require reprocessing to reflect map changes. It has been widely adopted in web and mobile applications requiring fast, reliable routing without relying on external real-time traffic feeds.

Licensing and ecosystem: OSRM is released under the BSD-3-Clause license. It is maintained by Project OSRM and a broader community, and has influenced the ecosystem of open-source routing engines through its emphasis on performance and offline capability.