How an address is written in Japan
An address in Japan is written in this order: street name and house number, then prefecture, then postal code, with the prefecture in capitals. The strongest check here is the postal code itself: GeoNames' postal code list (31 October 2026), with 142,577 postal codes for Japan, current codes only.
The order the lines go in
The parts are named rather than filled in: Spaw does not know an address in Japan and will not invent one. This block is produced by the same function that rewrites a real address, so the line order, the capitals Japan 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 PREFECTURE Postal code
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 | — |
| administrativeArea | Prefecture | required | yes |
| postalCode | Postal code | required | — |
In Japan the house number follows the street name, and that is the side it is written back on when the checker rewrites an address.
The table also carries a local layout for Japan, and it runs the other way round: the prefecture first and the street last. The order above is the Latin one, which is what an address rewritten here is written into. What local-script rendering means.
Can Spaw tell whether an address in Japan exists?
No. No address register is installed for Japan, so exists answers null: not evaluated, never no. An address can be perfectly formed and still not exist, and nothing here will pretend to know which.
A postcode directory answers a different question. The postal code is settled separately by GeoNames' postal code list, which is recorded as complete: one it does not hold answers postcode_not_found.
Further reading: How to read an address-existence answer.
Check an address in Japan
The same lookup the API runs, with Japan already selected.
Live demo
POST /demo/address · no key needed
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.
The postal code
Postal codes in Japan 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 \d{3}-?\d{4}
A postcode list from a multi-country source is installed for Japan, so a postal code here is not only checked for shape but looked up: 142,577 postal codes 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 Japan 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 Japan; 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 Japan, 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 | 私書箱, PO BOX, P O BOXthe operator's own words |
| general_delivery Held at the counter for collection | 郵便局留, 局留the operator's own words |
What can be checked for an address in Japan
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 JP | 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 Japan. A value that does not match answers invalid_postal_code. |
| postal code exists | yes | 142,577 postal codes 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 Japan, so an address with no marker answers street rather than unknown. |
| Street exists | no | No register is installed for Japan, so a street is neither confirmed nor denied: match_level answers null. |
| Building exists | no | No address register is installed for Japan, so exists answers null: not evaluated, never no. Absence is not evidence here. |
| Companies at the address | no | No open company register is installed for Japan, so companies_registered answers null and no mail-drop conclusion is drawn from a count. |
| Known mailbox branch | no | No operator branch list covers Japan, 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
- 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.
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