For the Leaflet maps we use the openstreetmap free service to convert addresses to coordinates.
It is their Nominatum service:
https://nominatim.openstreetmap.org/ui/search.html
You can call the API with an address and get the coordinate as results.
You can query any address, city
https://nominatim.openstreetmap.org/search?q=amsterdam&format=json
Or find Wappler address:
https://nominatim.openstreetmap.org/search?q=wappler&format=json
Maybe we can build a server action from so you can do it in batches server side and save the coordinates in database. But you can do it directly with the API action as well.