How an address is written in the Netherlands

An address in the Netherlands is written in this order: street name and house number, then postal code and town or city on one line. The strongest check here is a building-level one: Kadaster's Basisregistratie Adressen en Gebouwen (BAG) lists 10,078,006 addresses in the Netherlands (version 8 September 2026), which its publisher declares complete.

The order the lines go in

The parts are named rather than filled in: Spaw does not know an address in the Netherlands and will not invent one. This block is produced by the same function that rewrites a real address, so the line order, the capitals the Netherlands asks for and any text its operator prints on every envelope are the checker's own behaviour rather than a second description of it.

Organisation
Street name 12
Flat or unit
Postal code Town or city

No recipient line: nothing in the response is about a person, so the name the envelope carries is not part of what is checked.

field	called here	required	capitals
organization	Organisation	optional	—
addressLine1	Street name	required	—
addressLine2	Flat or unit	optional	—
locality	Town or city	required	—
postalCode	Postal code	required	—

In the Netherlands the house number follows the street name, and that is the side it is written back on when the checker rewrites an address. The postal code is written before the town.

Can Spaw tell whether an address in the Netherlands exists?

Yes. Kadaster's Basisregistratie Adressen en Gebouwen (BAG) lists 10,078,006 addresses in the Netherlands (version 8 September 2026). It is declared a complete address register, so an address it holds answers exists: true and one it does not answers exists: false. A false has two honest failure cases: a building added after the version in use, and an address spelled so differently from the register that no variant of its street matches. That is why a miss is scored rather than refused.

A postcode directory answers a different question. The postal code is confirmed separately by GeoNames' postal code list, which does not list every code, so one it does not hold is not flagged.

register	covers	lists	coverage	version
Kadaster's Basisregistratie Adressen en Gebouwen (BAG) nl-bag-adressen	Netherlands	10,078,006 addresses	complete	2026-09-08

Further reading: How to read an address-existence answer and How an open register locates a building.

Check an address in the Netherlands

The same lookup the API runs, with Netherlands already selected.

Live demo

POST /demo/address · no key needed

try:

Response

Look up any address to see the full API response, straight from the live service. The country decides which format it is read against.

Every field in the response Get your API key

The postal code

Postal codes in the Netherlands are checked against the pattern below rather than a description of it, because the shape is too particular to summarise without losing a case.

pattern [1-9]\d{3} ?(?:[A-RT-Z][A-Z]|S[BCE-RT-Z])

A postcode list from a multi-country source is installed for the Netherlands, so a postal code here is not only checked for shape but looked up: 4,086 postal code prefixes from GeoNames' postal code list, version 2026-10-31. It lists current codes only, so a retired code is not told apart from one it does not hold.

What the Netherlands calls an address that is not a front door

A PO box, a private mailbox and the other kinds of delivery point below are told apart by the words written on the address, never by a list of whose box is whose. The rows marked as the operator's own words are taken from the addressing guide of the postal operator in the Netherlands; the others are international spellings, not the operator's own. All of them are what the checker reads, and because an entry is carried for the Netherlands, an address here with none of them answers street.

address_type	written as
private_mailbox Private mailbox at a mail-receiving agency	PMBinternational spellings the checker also reads
po_box Post-office box	POSTBUSthe operator's own words
general_delivery Held at the counter for collection	POSTE RESTANTE, GENERAL DELIVERYinternational spellings the checker also reads
bulk_mail Business-volume arrangement	ANTWOORDNUMMERthe operator's own words

BUS look like box words in the Netherlands but name a flat or suite. They classify nothing; they only tell the parser where the unit is.

What can be checked for an address in the Netherlands

Read from the datasets this server holds right now, not written into the page. For most countries the answer is the written form and the postcode shape and nothing beyond them — in particular not the row people assume is always there.

check	for NL	what the answer means
Written form	yes	The address is split into the country's own parts and rewritten in the order above. A missing required part is named in one typed reason rather than a general failure.
postal code pattern	yes	Checked against the pattern the table carries for the Netherlands. A value that does not match answers invalid_postal_code.
postal code exists	yes	4,086 postal code prefixes from GeoNames' postal code list. It lists current codes only, so a retired code is not told apart from one it does not hold.
Kind of delivery point	yes	The operator's own box words are carried for the Netherlands, so an address with no marker answers street rather than unknown.
Street exists	yes	The address register carries every street its buildings stand on, so match_level answers street when the street is known and the building is not.
Building exists	yes	10,078,006 addresses in the Netherlands from Kadaster's Basisregistratie Adressen en Gebouwen (BAG), declared complete by its publisher, so a miss can answer exists: false.
Companies at the address	no	No open company register is installed for the Netherlands, so companies_registered answers null and no mail-drop conclusion is drawn from a count.
Known mailbox branch	no	No operator branch list covers the Netherlands, so is_mail_drop is never set from one here.
Post actually arrives	no	Not from this page, and not from open data in any country: whether post is delivered, and the vacant, residential and agency flags that go with it, are the postal service's own licensed product. Those fields answer deliverability_checked: false rather than a guess.

Null means not evaluated, never no.

Other countries

Sources

Google's Address Data Service · address-formats 2026-09-05© Google LLC, CC BY 4.0 (Google Address Data Service); initial import via commerceguys/addressing (MIT)
The postal operators' addressing guides · address-rules 2026-09-17
Kadaster's Basisregistratie Adressen en Gebouwen (BAG) · nl-bag-adressen 2026-09-08Basisregistratie Adressen en Gebouwen (BAG), Kadaster, CC0 1.0
GeoNames' postal code list · geonames-postal-codes 2026-10-31Postal codes, places and centroids from GeoNames (geonames.org), CC BY 4.0.

Data synced on 2026-10-31: the newest version among the datasets listed above.

Wrong result, or is it about you? If this tool said something you think is wrong, tell us and a person reads it. If Spaw is holding data about you and you never signed up here — a customer may have had your address verified, or reported that a message to it bounced — erase it yourself, confirmed by mail to that address and with no account needed.

More free tools

All free tools

Need this at scale?

The Spaw API runs the same check with batch and bulk endpoints, monitored address lists, your own suppression list and outcome reporting — 100 free credits a month, no card required.

Get your API key