postalcode

e.g.

$ curl -s https://japan-d2.github.io/postalcode/001/0000.json | jq
[
  {
    "postalCode": "0010000",
    "prefKana": "ホッカイドウ",
    "address1Kana": "サッポロシキタク",
    "address2Kana": "",
    "pref": "北海道",
    "address1": "札幌市北区",
    "address2": ""
  }
]