Mortgage & Loan Amortization Cal: POST /calculate
Give this API a loan amount, an interest rate, and a repayment term, and it hands back the precise monthly payment plus a complete schedule showing — for every single month — how much goes to interest, how much reduces the balance, and what you still owe. You can also ask 'what if I pay an extra $300 a month?' or 'what if I make a $10,000 lump payment in month 24?' and it will tell you exactly how many months you save and how much interest you avoid. Every number is computed with banker's rounding and a pinned arithmetic rule so that two correct systems running the same inputs produce identical results, down to the cent. No rate lookups, no market data — you supply the rate, the API does the math.
Start with a quote-only recipe. Payment signing stays in your project.
const response = await fetch("https://mortgage-amortization.underscoredone.com/calculate", {
method: "POST",
headers: { "content-type": "application/json" },
body: JSON.stringify({
"type": "http",
"method": "POST",
"bodyType": "json",
"bodyFieldNames": [
"annual_rate_percent",
"extra_monthly_payment",
"one_time_payments",
"principal",
"rounding",
"start_date",
"summary_only",
"term_months"
],
"pathParamNames": [],
"queryParamNames": []
}),
});
console.log(response.status);
console.log(Object.fromEntries(response.headers));
console.log((await response.text()).slice(0, 1000));
// A valid 402 is a quote, not a completed paid call.Review the provider input schema before running this non-read-only method. No payment code is included.
- Exact route checked
not safely testable · potentially-mutating-method:POST
- Origin reachable
HEAD https://mortgage-amortization.underscoredone.com/ returned 301.
- Observed in cdp-bazaar
The registry record was observed and retained with provenance.
EVIDENCE
Each record has an exact-route quote outcome. Unresolved templates and potentially mutating methods are labeled instead of being invoked without provider-specific test input. A quote is still separate from a settled paid call.