The API validates and complements filled-in postal code data for addresses located in The Netherlands. Therefore, you will always use the right address and prevent inconvenience during delivery.


All the necessary information for implementing this API.

Why use the Postalcode Check API

User experience
Postal code data is validated real-time, simplifying and accelerating the order process. This leads to a better user experience for customers, less return shipments and a higher conversion rate.

Easy to use
No need to fill in addresses completely in your checkout form. Entering postal code and house number is sufficient to automatically complete an address with street and city.

Correct data structure
Always the most recent and complete address data.

Get Started

Request your (Sandbox) API Key and start using the API.
As soon as you have an API key, it is recommended to run our Postman collections. Here you can find code examples of the various services and products we offer. This makes implementing the APIs much easier.


Using the API
The Checkout Postalcode Check provides an optimal way to implement the address verification in the webshop checkout.

General format (send any of a list of pre-defined fields). You can opt to require users to fill in a complete address (with all pre-defined fields that make up an address) or choose to choose a subset of fields. Unique Dutch addresses can be found based on the postalcode+housenumber+housenumberaddition (dependent on the existence of an housenumberaddition in the housenumber range). It can be attractive to use this subset instead of requiring users to fill out a complete address format.

Scenario 1; When a correct Postalcode, Housenumber (and Addition) combination was entered, the output should be a single output.

Scenario 2; When the Postalcode, Housenumber (and Addition) combination is not found, the output is an empty response. Like this: []