Compound Interest API

POST https://api.findutils.com/api/tools/compound-interest/execute

Compute compound interest growth. Supports any compound frequency (monthly, quarterly, annual) plus optional fixed monthly contributions. Returns final balance, total contributions, total interest, and a year-by-year balance series.

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Request body

application/json

principal

number required

Starting principal (in any currency).
annual_rate

number required

Annual interest rate as a decimal (0.07 = 7%).
years

number required

Investment duration in years.
compounds_per_year

integer optional

Compound periods per year. Default: 12 (monthly).
monthly_contribution

number optional

Optional fixed monthly contribution. Default: 0.

Example arguments

Verified

{
  "principal": 1000,
  "annual_rate": 0.05,
  "years": 5
}

curl -X POST https://api.findutils.com/api/tools/compound-interest/execute \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "principal": 1000,
    "annual_rate": 0.05,
    "years": 5
  }'

const response = await fetch('https://api.findutils.com/api/tools/compound-interest/execute', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json', Authorization: 'Bearer YOUR_API_KEY' },
  body: JSON.stringify({"principal":1000,"annual_rate":0.05,"years":5}),
});
const data = await response.json();

import requests

response = requests.post(
    "https://api.findutils.com/api/tools/compound-interest/execute",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={"principal":1000,"annual_rate":0.05,"years":5},
)
data = response.json()

$ch = curl_init('https://api.findutils.com/api/tools/compound-interest/execute');
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => ['Content-Type: application/json', 'Authorization: Bearer YOUR_API_KEY'],
    CURLOPT_POSTFIELDS => '{"principal":1000,"annual_rate":0.05,"years":5}',
    CURLOPT_RETURNTRANSFER => true,
]);
$data = json_decode(curl_exec($ch), true);

Also an MCP tool

Call compound_interest from Claude, Cursor or any MCP client. Same arguments, same output.

https://mcp.findutils.com

MCP reference

Rate limit: 60 a minute, per IP
Auth: API key
REST id: compound-interest
MCP name: compound_interest
Category: Finance
Machine-readable: openapi.json · markdown.md

Request body

Example arguments

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