Free Financial Calculator API for Developers
8 endpoints. JSON responses. No API key required for free tier.
API Documentation → GitHub Repo →Why Another Calculator API?
Most financial calculation APIs either cost $50+/month, require complex OAuth setup, or return XML from 2008. We built the CalcLeap API to be dead simple: make a GET request, get back clean JSON.
It covers the calculations developers actually need: mortgage payments with amortization schedules, compound interest projections, retirement planning, insurance estimates by state, BMI, and more.
Quick Example
$ curl "https://calcleap.com/api/mortgage?principal=350000&rate=6.5&years=30"
{
"calculator": "mortgage",
"result": {
"monthlyPayment": 2212.24,
"totalPaid": 796405.71,
"totalInterest": 446405.71,
"loanTermMonths": 360,
"schedule": [...]
}
}Available Endpoints
Mortgage Calculator
GET /api/mortgage
| Param | Type | Description |
|---|---|---|
| principal | number | Loan amount ($) |
| rate | number | Annual interest rate (%) |
| years | number | Loan term in years |
Returns: monthly payment, total paid, total interest, 12-month amortization schedule.
Compound Interest
GET /api/compound
| Param | Type | Description |
|---|---|---|
| principal | number | Starting amount ($) |
| rate | number | Annual return (%) |
| years | number | Investment period |
| contribution | number | Monthly addition ($) |
Returns: future value, total contributed, total interest, year-by-year growth.
Insurance Estimator
GET /api/insurance
| Param | Type | Description |
|---|---|---|
| type | string | auto or home |
| state | string | US state code (NJ, CA, TX...) |
| age | number | Driver age (auto only) |
| coverage | string | full or liability |
Returns: annual/monthly premium estimate, state average. All 50 states supported.
Retirement Planner
GET /api/retirement
| Param | Type | Description |
|---|---|---|
| currentAge | number | Your current age |
| retireAge | number | Target retirement age |
| monthlyContribution | number | Monthly savings ($) |
| currentSavings | number | Existing savings ($) |
| annualReturn | number | Expected return (%, default 7) |
Returns: projected savings, estimated monthly retirement income (4% rule).
BMI Calculator
GET /api/bmi
| Param | Type | Description |
|---|---|---|
| weight | number | Weight (lbs or kg) |
| height | number | Height (inches or cm) |
| unit | string | imperial or metric |
+ Loan, Tip, Percentage
Three more endpoints for general calculations. See full docs →
Code Examples
JavaScript (fetch)
const res = await fetch('https://calcleap.com/api/mortgage?principal=400000&rate=7&years=30');
const data = await res.json();
console.log(`Monthly payment: $${data.result.monthlyPayment}`);Python (requests)
import requests
r = requests.get('https://calcleap.com/api/compound', params={
'principal': 10000, 'rate': 8, 'years': 25, 'contribution': 300
})
print(f"Future value: ${r.json()['result']['futureValue']:,.2f}")cURL
curl "https://calcleap.com/api/insurance?type=auto&state=CA&age=30"Pricing
| Plan | Requests | Price |
|---|---|---|
| Free | 100/day | $0 |
| Pro | 10,000/day | $9/month |
| Enterprise | Unlimited | Contact us |
Get Started
No API key needed for the free tier. Just start making requests.
Read the Docs → Star on GitHub →