What is the difference between the Autocomplete or Validate API vs. Dutch Postcode API?

With the Autocomplete or Validate API, you can request addresses from all available countries. These APIs are more extensive than the Dutch Postcode API in terms of functionality. For example, you can not only complete Dutch addresses based on a postcode and house number, but you can also complete them using the auto-complete functionality. Handy if addresses are entered where the postcode is unknown. The Dutch Postcode API works with only a postcode and house number to return a full address.

Can I use only 1 API?

You can, of course, use all APIs side-by-side. For example, addresses for your international customers can be retrieved via the Autocomplete or Validate API, and for Dutch customers via the Dutch Postcode API. In some plugins, this is already done automatically; it chooses the correct API for when an address is requested. 

Why is the Dutch Postcode API cheaper?

Dutch addresses retrieved via the Autocomplete or Validate API have a higher unit price because these APIs offer more functionality. Even if a Dutch postcode and house number request is made on the Autocomplete or Validate API, that rate applies.