Calculators Loan Payment Calculator

{
  "result": {
    "answer": "1,520.06 / month",
    "answerLabel": "360 monthly payments",
    "details": [
      {
        "label": "Total repaid",
        "value": "547,220.13"
      },
      {
        "label": "Total interest",
        "value": "247,220.13"
      },
      {
        "label": "Interest as % of principal",
        "value": "82.41%"
      }
    ],
    "steps": [
      "r = 4.5% ÷ 12 = 0.375% monthly",
      "n = 30 × 12 = 360 payments",
      "M = P · r · (1+r)ⁿ ÷ ((1+r)ⁿ − 1) = 1,520.06"
    ],
    "value": 1520.055929
  },
  "tool": "loan-payment-calculator"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://agentstoolshub.com/api/v1/calculators/loan-payment-calculator?annualRate=4.5&principal=300000&years=30'

# 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 - 'https://agentstoolshub.com/api/v1/calculators/loan-payment-calculator?annualRate=4.5&principal=300000&years=30' \
  | 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 $0.003 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.003" });
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 $0.003 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fagentstoolshub.com%2Fapi%2Fv1%2Fcalculators%2Floan-payment-calculator
const res = await pay("https://agentstoolshub.com/api/v1/calculators/loan-payment-calculator?annualRate=4.5&principal=300000&years=30");
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 $0.003 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.003"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://agentstoolshub.com/api/v1/calculators/loan-payment-calculator?annualRate=4.5&principal=300000&years=30")
    print(res.status_code, res.text)