GraphHopper is a fast, memory-efficient routing engine for road networks, primarily using OpenStreetMap data. It can be embedded as a Java library or run as a standalone server that exposes HTTP endpoints for routing and related geospatial calculations.

Key Features

Multi-profile routing (e.g., car, bike, walking) with support for custom routing profiles
Turn-by-turn instructions plus distance/time calculation and road attribute handling
Isochrone generation for travel-time or travel-distance reachability analysis
Map matching (“snap to road”) for aligning noisy GPS tracks to the road network
Optional public transit support using GTFS data
Designed for high performance on large datasets through preprocessing and efficient graph storage

Use Cases

Self-hosted routing backend for web or mobile navigation applications
Logistics, fleet, and field-service systems that need fast route and ETA computation
Geospatial analytics such as service-area and accessibility analysis using isochrones

Limitations and Considerations

Importing and preprocessing large OpenStreetMap extracts can require significant RAM, CPU, and disk
Offline mobile usage is not officially supported in newer versions (though it may still work)

GraphHopper is well-suited for teams that want control over routing behavior and data sources while keeping performance high. It fits both embedded Java use and service-oriented deployments that need reliable, customizable routing at scale.