The Dutch National SDI (PDOK) is a central facility for unlocking geodatasets of national importance. This is actual and reliable information for both the public and private sector.
PDOK provides API's, for instance Locatieserver. Locatieserver is a very powerfull geocoding service. Upon request it will return the location of an adress, street, place, neighbourhood, district, municipality, province, property boundary, highway number or hectometer marker.
There doesn't necessarily has to be a 100% match with the names and adresses in the PDOK geodatasets. Every search result will have a score indicating the level of success.
Soon Locatieserver will also support reverse geocoding. Reverse geocoding is already available in bèta.
Major advantage of Locatieserver compared to other geocoding services like Google and OpenStreetMap, is that it will also return the official adresses and names. Moreover it will return unique identifiers to link the search results to other sources of information within government. Also the data is updated frequently. For instance, adresses are updated daily.
Although you have to register to acquire an API-key, using Locatieserver is free of charge. I don't think there is a maximum number of requests per day, like with the Google API. There is a fair use policy.
So I think you can see why I am enthousiastic about Locatieserver ;-) However usage outside of the GIS community seems to be limited. So I would like to create a wrapper making it easier to use Locatieserver in R.
Alas all documentation is in Dutch.
Please contact me at w (dot) tadema (at) provinciegroningen (dot) nl