How to make a reverse geocoding service - converting coordinates to an address?

Question

Geolocation

To use geolocation in a mobile application, you need to implement the Geodecoding service (Geodecoding or Reverse Geocoding).
The task is actually very straightforward: using the given latitude and longitude coordinates, determine the country, city, places within which the given point is located.
A clear explanation is here: https://developers.google.com/maps/documentation/g...
Questions:
1. What public web services (other than the mentioned google) exist to solve the problem?
2. What is the best way to implement the service yourself?
People recommend PostgreSQL + PostGIS + geonames.org. Is this a solution to the question, can it be made simpler/better/more relevant?

Answer 1

Easiest :
Buy a droplet on DO, put OSRM there and use it.
And its own, and almost free.