Jp Mortgage

{
  "as_of": null,
  "assumptions": [],
  "billable": true,
  "breakdown": [],
  "carried_forward": [],
  "disclaimer": "仮定条件に基づく概算試算。税務相談・手続代行・法律相談ではない。申告・届出への使用不可。確定額は官公署または税理士・社会保険労務士等に確認のこと。",
  "not_covered": [
    "住宅ローン控除(年度別上限・省エネ区分)",
    "団信・手数料",
    "変動金利の将来予測"
  ],
  "note": "SAMPLE RESPONSE generated by the exact deterministic engine that serves production (jp-statutory has no LLM: same input always produces this byte-identical result, carrying the same rules_version and cited primary sources). Served free at /samples/{product} so you can verify the response shape, the rules_version field and the source citations before paying. No payment was taken. The sample_input shown is the catalog example input that produced this output.",
  "ok": true,
  "result": {
    "method": "level_payment",
    "monthly_payment_yen": 102095,
    "months_paid": 421,
    "schedule_head": [
      {
        "balance_yen": 34932905,
        "interest_yen": 35000,
        "month": 1,
        "payment_yen": 102095,
        "principal_yen": 67095
      },
      {
        "balance_yen": 34865742,
        "interest_yen": 34932,
        "month": 2,
        "payment_yen": 102095,
        "principal_yen": 67163
      },
      {
        "balance_yen": 34798512,
        "interest_yen": 34865,
        "month": 3,
        "payment_yen": 102095,
        "principal_yen": 67230
      }
    ],
    "schedule_tail": [
      {
        "balance_yen": 102149,
        "interest_yen": 204,
        "month": 419,
        "payment_yen": 102095,
        "principal_yen": 101891
      },
      {
        "balance_yen": 156,
        "interest_yen": 102,
        "month": 420,
        "payment_yen": 102095,
        "principal_yen": 101993
      },
      {
        "balance_yen": 0,
        "interest_yen": 0,
        "month": 421,
        "payment_yen": 156,
        "principal_yen": 156
      }
    ],
    "total_interest_yen": 7880056,
    "total_paid_yen": 42880056,
    "total_prepaid_yen": 0
  },
  "rules_version": "2026.08.18",
  "sample": true,
  "sample_input": {
    "annual_rate": 0.012,
    "months": 420,
    "principal_yen": 35000000
  },
  "sources": [
    "deterministic-annuity-math"
  ],
  "summary": "借入35,000,000円・年1.200%・420回 -> 毎月102,095円、総利息7,880,056円",
  "tool": "jp-mortgage",
  "unverified_rules": []
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://mart402.com/v1/jp-mortgage' \
  -H 'content-type: application/json' \
  --data-raw '{"annual_rate":0.012,"months":420,"principal_yen":35000000}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://mart402.com/v1/jp-mortgage' \
  -H 'content-type: application/json' \
  --data-raw '{"annual_rate":0.012,"months":420,"principal_yen":35000000}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.005 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.005" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.005 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fmart402.com%2Fv1%2Fjp-mortgage&method=POST
const res = await pay("https://mart402.com/v1/jp-mortgage", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "annual_rate": 0.012,
    "months": 420,
    "principal_yen": 35000000
  }),
});
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.005 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.005"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://mart402.com/v1/jp-mortgage",
        json={
            "annual_rate": 0.012,
            "months": 420,
            "principal_yen": 35000000,
        },
    )
    print(res.status_code, res.text)