API documentation

Adrescheck Internationaal v3 (Dec21)

Summary

Use this API to validate international address data, including the Netherlands, that is entered in your webshop or CRM.

Methods and endpoints

Method	Endpoint
POST	https://api.postnl.nl/address/international/v3/validate

Required headers

Header key	Header Value	Mandatory / optional
apikey	Your apikey	Mandatory
content-type	application/json	Mandatory

Input parameters

Fieldname	Mandatory/optional	Format	Example
CountryIso	Mandatory	String [2] or [3], according to ISO 3166-1 ‘alpha-2’ and ‘alpha-3’, not ‘numeric-3’.	BE/BEL
City	Recommended	String [0-50]	Antwerpen
PostalCode	Recommended	String [0-16]	2000
Street	Recommended	String [0-50]	Oude Koornmarkt
HouseNumber	Recommended	String or Number [0-8]	39
HuseNumberAddition	Optional	String [0-50]	A
Building	Optional	String [0-50]	De molensteen
Flat	Optional	String [0-50]	Flat 2
Stair	Optional	String [0-50]	3
Floor	Optional	String [0-50]	2
Door	Optional	String [0-50]	C
Bus	Optional	String [0-50]	1

Supported countries

This API supports over 250 countries, regions, island groups. You can download the list here (link to pdf file ‘Country codes ISO 3166-1') or find a general list of county ISO codes here.

Download documentation

Input field ‘strength’ per country

Address formatting is different per country. Therefore, input data fields can be more (or less) indicative of an address. We use that varying field indication ‘strength’ in our queries as well. For the most requested countries, these are the indication strengths of input fields. This overview will be updated regularly.

	CountryISO	Street	HouseNumber	HouseNumberAddition	PostalCode	City	Building
Austria	Mandatory	Strong	Very strong	Normal	Very strong	Strong	Normal
Belgium	Mandatory	Strong	Very strong	Normal	Very strong	Strong	Normal
France	Mandatory	Strong	Very strong	Normal	Very strong	Strong	Normal
Germany	Mandatory	Strong	Very strong	Normal	Very strong	Strong	Normal
United Kingdom	Mandatory	Strong	Very strong	Normal	Very strong	Strong	Strong
Netherlands	Mandatory	Strong	Very strong	Normal	Very strong	Strong	Normal
Spain	Mandatory	Strong	Very strong	Normal	Very strong	Strong	Normal

Output parameters

All fields are returned for every API call. If no data was found for a specific field, the value null will be returned.

Fieldname	Description of attribute	Format [length]
ResultNumber	The number of results (multiple addresses in the response is temporarily unavailable)	Number [0-5]
MailabilityScore	Indication of certainty that the address is mailable	Number [0-3]
ResultPercentage	Level of similarity between the input and output address data	Number [0-3]
FormattedAddress	The full address according to local/national formatting standards	Array of strings, dependent on formatting standards
Street	Street name of the address	String [0-95]
HouseNumber	House number of the address	Number [0-35]
HouseNumberAddition	House number addition of the address	Number [0-35]
PostalCode	Postal code of the address	String [0-20]
City	City of the address	String [0-35]
Country	Country of the address	String [0-95]
CountryIso2	ISO 3166-1 alpha-2 code of the country of the address	String [2]
CountryIso3	ISO 3166-1 alpha-3 code of the country of the address	String [3]
CompanyName	Name of company, when located on the address	String [0-95]
Building	Name of the building	String [0-95]
Flat	Flat number of the address	String [0-50]
Stair	Stair that the address is connected to	String [0-50]
Floor	Floor that the address is located on	String [0-50]
Door	Door of the address	String [0-50]
Bus	Bus field; used for Belgium addresses	String [0-50]
Locality	Locality of the address	String [0-95]
State	State of the address	String [0-95]
Latitude	Latitudinal coordinate of address	Number [0-15]
Longitude	Longitudinal coordinate of address	Number [0-15]

ResultNumber

Result Number is defined as an incremental identification number of the results. When there is one address in the output response, the result number is 1. When there is more than one address in the output response, the addresses are sorted based on the result score. The first address in the response will have a result number of 1, the second address in the output will have a result number of 2, and so on.

The mailability score (MS) is defined as how well we are able to match a given input address to an address in our address database and also based on the completeness of the input and output. Scores from 0 to 100 are given back in the output. If there are different possible matches to the input provided, then the mailability score varies due to that. What each score means, is shown in the table below.

Score	Defintion
100	Exact unique match
80	Almost exact match. In most cases just 1 element missing, such as a postcode or streetname, but match is still unique.
60	Lot of discrepancies, but unique match with our database. 5-10
40	Housenumber missing and less than 10 - 20 possible results.
20	Housenumber missing more than 20 possible results.
0	No results.

The result percentage tells us how much the output has changed from the input. The score varies from 0 to 100. This is based on a multi-dimensional Levenshtein distance function. Levenshtein distance is a string metric for measuring the difference between two sequences. A score of 100 indicates a perfect match and a score of 0 indicates a complete mismatch. We do a Levenshtein on the input parameter and output of the city name, street name, and postcode.

An example: Let’s take an existing valid address such as Transformatorweg 102, 1014AK, Amsterdam. The following scenarios demonstrate how the result Scores will vary when city name, street name or postcode is different between the input and output.

Address Input: Transformatorweg 102, 1014AK, Amsterplaats Address Output: Transformatorweg 102, 1014AK, Amsterdam Result Score: 89 Transformatorweg 102, 1014AK, Amsterplaats does not exist. The input had a wrong city name of Amsterplaats. It was a change from the correct city name of Amsterdam in the output. So the result score was reduced from a perfect 100 to 89
Address Input: Transformatorweg 102, 1014XB, Amsterdam Address Output: Transformatorweg 102, 1014AK, Amsterdam Result Score: 87 Transformatorweg 102, 1014XB, Amsterdam does not exist. The input had a wrong postcode once again of 1014XB. Since there are two characters different from the right postcode, the result score is further reduced to 87. MX IAC Fields 2
Address Input: Transformatorstraat 102, 1014AK, Amsterdam Address Output: Transformatorweg 102, 1014AK, Amsterdam Result Score: 91 Transformatorstraat 102, 1014AK, Amsterdam does not exist. The input had a wrong streetname of Transformatorstraat. Since the last part of the streetname are different from the right streetname, the result score is reduced to 91.

Example request & response

Request

Response

{

"City": "Antwerpen",

"PostalCode": "2600",

"Street": "Grotesteenweg",

"HouseNumber": "521",

"Bus": "2",

"CountryIso": "BE",

}

[

{

"ResultNumber": 1,

"MailabilityScore": 100,

"ResultPercentage": 100,

"FormattedAddress": [

"Bus 2",

"Grotesteenweg 521",

"2600 Antwerpen"

"Belgium"

"Street": "Grotesteenweg",

"HouseNumber": 521,

"HouseNumberAddition": null,

"PostalCode": "2600",

"City": "Antwerpen",

"Country": "Belgium",

"CountryIso2": "BE",

"CountryIso3": "BEL",

"CompanyName": null,

"Building": null,

"Locality": "Berchem",

"State": "Antwerpen",

"Latitude": 51.1807092419929,

"Longitude": 4.4316843863965,

"Flat": null,

"Stair": null,

"Floor": null,

"Door": null

"Bus": "2"

}

]

Possible error codes

Error code	Error message
200	JSON response with requested data.
200	Address not found. Example: []
4xx	Error on customer-side. Example: { "errors": [ { "status": "400", "title": "Bad Request", "detail": "Query must include valid CountryIso" } ] }
5xx	Error on PostNL side.