OSMR (Open Source Routing Machine)
- **Modern C++ routing engine for shortest paths in road networks. **
- Flexible import of OpenStreetMap data/maps
- 100% Free
https://afi.io/blog/introduction-to-osrm-setting-up-osrm-backend-using-docker/
Google S2 lib
https://www.gojek.io/blog/appreciating-the-geo-s2-library
https://blog.christianperone.com/2015/08/googles-s2-geometry-on-the-sphere-cells-and-hilbert-curve/
https://medium.com/tinder/geosharded-recommendations-part-1-sharding-approach-d5d54e0ec77a
https://www.uber.com/en-BR/blog/gairos-scalability/