Amortise a fixed-rate loan and show the impact of an optional monthly extra payment on payoff time and total interest.
This page documents the HTTP endpoint POST /api/tools/loan-calculate/execute. See the MCP reference →
Call it over REST
POST https://api.findutils.com/api/tools/loan-calculate/execute · no API keys · 60 requests/min per IP
Execute — verified arguments
curl -X POST https://api.findutils.com/api/tools/loan-calculate/execute \
-H "Content-Type: application/json" \
-d '{
"principal": 10000,
"annual_rate": 0.05,
"years": 5
}'Parameter schema for this endpoint
curl https://api.findutils.com/api/tools/loan-calculateInput schema
| Argument | Type | Required | Description |
|---|---|---|---|
| principal | number | yes | Loan balance. |
| annual_rate | number | yes | Annual interest rate as a decimal. |
| years | number | yes | Contract length in years. |
| extra_payment | number | no | Optional monthly extra paid on top of the standard payment. |
Example arguments (verified)
{
"principal": 10000,
"annual_rate": 0.05,
"years": 5
}Also an MCP tool
Claude, Cursor, and any MCP client can call this tool as
findutils:loan_calculate after one connect command.
Connect once
claude mcp add findutils --transport http https://mcp.findutils.com/More Finance tools
Amortization Calculator
Return a full loan amortization schedule (one row per month with payment, principal, interest, extra payment, balance) plus totals, interest
Auto Loan Calculator
Return the monthly car payment, total interest, financed amount, and a month-by-month amortization schedule for an auto loan.
Break Even Calculator
Return the break-even point of a product or business: contribution margin, contribution margin ratio, break-even units and revenue, plus the
Business Loan Calculator
Return the monthly payment, total interest, origination fee, effective yearly rate (interest plus fees), a yearly summary, and a full monthl
Compound Interest
Compute compound interest growth.
Credit Card Payoff Calculator
Return how long a credit card balance takes to pay off at a fixed monthly payment (mode "payment"), or the payment needed to clear it in a t
Credit Card Validate
Validate a credit card number with the Luhn checksum and detect the brand.
Debt Payoff Calculator
Return a debt payoff plan for several debts using the avalanche (highest rate first) or snowball (lowest balance first) strategy: total mont