Postal code lookup

Resolve Japanese postal codes into developer-ready address data.

A seven-digit Japanese postal code usually identifies a town area, not a complete deliverable address. This API returns the official postal candidate plus structured address evidence and tells you when a code maps to multiple results.

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Built in Japan · English-first JSON · Official and public source provenance · No government endorsement claimed

NO SIGN-UP · NO API KEY

Try a postal code without an account

Use 100-0005 or paste a full address containing a postal code. Review candidates before copying the production request.

Try it free — no signup

Make a Japanese address usable

Enter one address and see how Japan Address Mix organizes it. Start with a sample if you like.

No API key · Rate limited · Inputs are not saved

Japanese address

Try a sample

You can use Japanese characters, a postal code, or a full address.

Your easy-to-read result appears here.

No account, API knowledge, or card is needed.

PRODUCTION REQUEST

Copy a request, then inspect the actual response contract.

The free key uses the same documented endpoint. Put the secret in a server-side environment variable and never commit it.

curl -X POST https://api.japanapistore.com/v1/address/resolve \
  -H "Authorization: Bearer ${JAPAN_API_KEY}" -H "Content-Type: application/json" \
  -d '{"query":"100-0005"}'

Representative responseFields depend on evidence and input.

{"success":true,"match":{"status":"matched","precision":"town_area"},"address":{"postal_code":"1000005","prefecture":"東京都","municipality":"千代田区","town_area":"丸の内"},"sources":[{"provider":"japan_post","status":"matched"}]}

SOURCES, FRESHNESS, LIMITS

Evidence you can inspect—not a black-box “Japan answer.”

The response names the active Japan Post dataset and any Digital Agency evidence used for enrichment.

Japan Post

Used for: Postal codes, prefectures, municipalities, town areas and kana.
Freshness: The active source version is returned in API provenance.
Transformation: JAPAN API STORE normalizes fields and reconciles them with Digital Agency address evidence.

Digital Agency Address Base Registry

Used for: Structured Japanese address identifiers, hierarchy and coordinates where public evidence exists.
Freshness: Dataset version and source status are returned separately from Japan Post.
Transformation: Matches are graded without treating coordinate precision as address precision.

FREE DEVELOPER TIER

Use the demo now. Create a key only when you are ready to build.

No credit card for the free key. One dashboard gives access to the four existing APIs.

Get a free API key First 200 OK guide OpenAPIPostman