For developers

Free car-cost API

The same verified formulas behind our calculators, as JSON. No API key and no sign-up. Two conditions: stay under 60 requests/minute per IP, and if you publish figures from this API, show the attribution link that comes with every response — full terms at /api-terms. Prefer a drop-in UI? Use a free widget instead.

GET`/api/v1/loan-payment`

Fixed-rate auto-loan amortization: monthly payment, total interest and amount financed — identical math to our Auto Loan Calculator.

Param	Required	Description
price	yes	Vehicle price in USD (0–2,000,000).
rate	yes	APR as a percentage, e.g. 7.5 (0–50).
term	yes	Loan term in months (1–120).
down	no	Down payment in USD. Default 0.
trade	no	Trade-in value in USD. Default 0.
trade_credit	no	State trade-in tax rule: 1 = full credit (default, most states), 0 = no credit (CA, VA, HI), or a dollar cap (MI: 12000).
tax	no	Sales-tax percentage, applied after the creditable trade-in per trade_credit. Default 0.

curl "https://themotorcrunch.com/api/v1/loan-payment?price=32000&down=4000&rate=7.5&term=60&tax=6"

{
  "endpoint": "/api/v1/loan-payment",
  "result": {
    "monthly_payment": 599.54,
    "total_interest": 6052.13,
    "amount_financed": 29920,
    "currency": "USD"
  },
  "attribution": {
    "required": true,
    "html": "Data by <a href=\"https://themotorcrunch.com/car-financing/auto-loan-calculator\">MotorCrunch</a>",
    "url": "https://themotorcrunch.com/car-financing/auto-loan-calculator"
  }
}

GET`/api/v1/tax-and-fees`

True out-the-door price under real state rules: trade-in tax credit, doc-fee taxability and statutory tax caps — identical math to our Car Tax & Fees Calculator.

Param	Required	Description
price	yes	Vehicle price in USD (0–2,000,000).
tax	yes	Sales-tax percentage, e.g. 6.5 (0–20).
trade	no	Trade-in value in USD. Default 0.
trade_credit	no	State trade-in tax rule: 1 = full credit (default, most states), 0 = no credit (CA, VA, HI), or a dollar cap (MI: 12000).
tax_cap	no	Statutory dollar cap on the vehicle tax itself (SC: 500). Default 0 = uncapped.
reg_fee	no	Registration + title fees in USD. Default 0.
doc_fee	no	Dealer doc fee in USD. Default 0.
doc_taxed	no	1 = doc fee sits inside the taxable base (e.g. CA); 0 = excluded when separately stated (e.g. TX). Default 0.

curl "https://themotorcrunch.com/api/v1/tax-and-fees?price=32000&tax=6.5&reg_fee=350&doc_fee=500"

{
  "endpoint": "/api/v1/tax-and-fees",
  "result": {
    "sales_tax": 2080,
    "total_taxes_fees": 2930,
    "out_the_door": 34930,
    "taxable_amount": 32000,
    "currency": "USD"
  },
  "attribution": {
    "required": true,
    "html": "Data by <a href=\"https://themotorcrunch.com/car-financing/car-tax-and-fees-calculator\">MotorCrunch</a>",
    "url": "https://themotorcrunch.com/car-financing/car-tax-and-fees-calculator"
  }
}

GET`/api/v1/cost-per-mile`

True operating cost per mile (fuel + maintenance + depreciation + insurance) — identical math to our Cost Per Mile Calculator, the number every gig-driving article needs.

Param	Required	Description
annual_miles	yes	Miles driven per year (1–500,000).
fuel_price	yes	Fuel price in USD per gallon.
mpg	yes	Vehicle fuel economy in MPG (1–200).
maintenance	no	Maintenance + tires per year, USD. Default 0.
depreciation	no	Depreciation per year, USD. Default 0.
insurance	no	Insurance per year, USD. Default 0.

curl "https://themotorcrunch.com/api/v1/cost-per-mile?annual_miles=30000&fuel_price=3.40&mpg=28&maintenance=1400&depreciation=3200&insurance=1800"

{
  "endpoint": "/api/v1/cost-per-mile",
  "result": {
    "total_cost_per_mile": 0.3348,
    "annual_operating_cost": 10042.86,
    "fuel_cost_per_mile": 0.1214,
    "currency": "USD"
  },
  "attribution": { "required": true, "url": "https://themotorcrunch.com/car-rideshare/cost-per-mile-driving-calculator" }
}

JavaScript example

const res = await fetch(
  "https://themotorcrunch.com/api/v1/loan-payment?price=32000&rate=7.5&term=60"
);
const data = await res.json();
console.log(data.result.monthly_payment); // 641.21
// Publishing this number? Render data.attribution.html next to it (required):
document.querySelector("#credit").innerHTML = data.attribution.html;

Attribution snippet (required when you publish figures)

Every response includes an attribution object. Render its html — or this equivalent — anywhere visible on the page that shows the numbers:

Data by <a href="https://themotorcrunch.com/car-financing/auto-loan-calculator">MotorCrunch</a>

MCP server (for AI assistants)

MotorCrunch is also a Model Context Protocol server. Point any MCP-compatible AI client at the endpoint below and it can call our calculators as tools — running the same deterministic math the site uses, so the model never invents the numbers.

MCP endpoint (Streamable HTTP, JSON-RPC 2.0):
POST https://themotorcrunch.com/api/mcp

Tools: calculate_auto_loan, calculate_tax_and_fees,
       analyze_dealer_quote, keep_repair_or_replace
Protocol: 2025-06-18 (also 2025-03-26, 2024-11-05)

# Discover tools:
curl -X POST https://themotorcrunch.com/api/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

Limits & guarantees

• 60 requests/minute per IP; over that you get HTTP 429 with Retry-After. Standard X-RateLimit-* headers on every response.
• CORS is open (Access-Control-Allow-Origin: *) — call it straight from the browser.
• Figures are estimates from standard published formulas (documented on our methodology page) — never quotes or financial advice.
• Versioned under /api/v1/; breaking changes get a new version.
• Full terms: https://themotorcrunch.com/api-terms.