Nominatim – is a free software that allows to make forward geocoding (search location by name, address) and reverse geocoding (retrieve postal address or place name by known coordinates).
The advantage of using Nominatim with Navixy On-premise is that it can be deployed on your local server, thus won’t limit you in amount of requests. You can still use other sources for geocode in parallel (e.g. Google), but they might seem rather expensive or not meeting your needs in specific regions.
Hardware requirements will heavily depend on the amount of data you plan to maintain. For example, installing data only for one country or one continent takes much less resources than data for the whole globe.
You can download Nominatim from it’s official web page:
There, you can find hardware and software requirements, as well as detailed installation manual:
Also, official Nominatim GitHub page: