OpenRouteService uses GraphHopper as library which uses exact routing algorithms: https://github.com/graphhopper/graphhopper https://github.com/graphhopper/grap

OpenRouteService uses GraphHopper as library which uses exact routing algorithms: https://github.com/graphhopper/graphhopper https://github.com/graphhopper/graphhopper (note: I'm one of the co-founders of GraphHopper) And then this A to B routing gives you the distance matrix which is necessary as input for vehicle routing algorithms (usually heuristics), see https://www.graphhopper.com/blog/2017/09/18/route-optimization-explained/ https://www.graphhopper.com/blog/2017/09/18/route-optimizati... for more details.