get https://us1.locationiq.com/v1/optimize//
Optimize API solves the Traveling Salesman Problem(TSP) using a greedy heuristic (farthest-insertion algorithm) for 10 or more waypoints and uses brute force for less than 10 waypoints. The returned path does not have to be the fastest path. As TSP is NP-hard it only returns an approximation. Note that all input coordinates have to be connected for the optimize service to work.