# Auto Loan Interest Rates API

> Current interest rates for auto loans, leases, and other financing options.

Interest Rates returns current auto loan APRs for a vehicle by VIN, for terms from 36 to 84 months. Send GET /apr/{vin} with the year, make, model, the buyer's ZIP code and credit score, and your API key. It is available from the Growth plan at $0.005 per call, or $0.004 on Scale.

## Endpoint

`GET https://api.auto.dev/apr/{vin}`

- `vin` (path): 17-character Vehicle Identification Number (letters and digits, excluding I, O, and Q). Format: `[A-HJ-NPR-Z0-9]{17}`.
- `year` (query, required): Model year of the vehicle.
- `make` (query, required): Vehicle make.
- `model` (query, required): Vehicle model.
- `zip` (query, required): Buyer's ZIP code.
- `creditScore` (query, required): Buyer's credit score.
- `vehicleAge` (query, optional): Vehicle age in years.
- `vehicleMileage` (query, optional): Vehicle mileage.

Authenticate with `Authorization: Bearer <key>`, `?apiKey=<key>` or `X-API-Key: <key>`.

```sh
curl "https://api.auto.dev/apr/1C4HJXEN5MW592818?year=2021&make=Jeep&model=Wrangler&zip=37129&creditScore=720&vehicleAge=3&vehicleMileage=36000" \
  -H "Authorization: Bearer $AUTODEV_API_KEY"
```

## What it returns

- APR by term, 36 to 84 months
- Credit score used
- ZIP code
- Vehicle age and mileage

Response:

```json
{
  "vehicle": {
    "vin": "1C4HJXEN5MW592818",
    "year": 2021,
    "make": "Jeep",
    "model": "Wrangler"
  },
  "zip": "37129",
  "creditScore": "720",
  "vehicleAge": 3,
  "vehicleMileage": "36000",
  "apr": {
    "36": 7.644,
    "48": 7.644,
    "60": 7.524,
    "72": 7.663,
    "84": 8.263
  }
}
```

## Pricing

- Free: not available on this plan, 5 requests per second
- Growth: $0.005 per call, 10 requests per second
- Scale: $0.004 per call, 50 requests per second

## Use it from an AI agent

Hosted MCP server (recommended): https://mcp.auto.dev/mcp, named `auto-dev`. Sign-in is OAuth on first use, so agents never handle an API key.

- Claude Code: `claude mcp add --transport http auto-dev https://mcp.auto.dev/mcp`. Then run /mcp in Claude Code and choose Authenticate for auto-dev.
- Claude Desktop: In Settings, open Connectors, choose Add Custom Connector, name it auto-dev and paste https://mcp.auto.dev/mcp, then sign in
- Cursor (~/.cursor/mcp.json): `{"mcpServers":{"auto-dev":{"url":"https://mcp.auto.dev/mcp"}}}`. Restart Cursor. Sign-in opens on the first tool call.
- VS Code (.vscode/mcp.json): `{"servers":{"auto-dev":{"type":"http","url":"https://mcp.auto.dev/mcp"}}}`. For Copilot agent mode, VS Code 1.99 or later. Sign-in opens on first use.
- Windsurf (~/.codeium/windsurf/mcp_config.json): `{"mcpServers":{"auto-dev":{"serverUrl":"https://mcp.auto.dev/mcp"}}}`. Restart Windsurf. Sign-in opens on the first tool call.
- Grok Bot: send `Add a custom MCP server called auto-dev at https://mcp.auto.dev/mcp`. Confirm, then choose Authorize and sign in. Type @auto-dev in a chat to use it.
- Muse: send `Connect Auto.dev`. Or open Settings, then Connectors, and choose Connect next to Auto.dev. Sign in when asked.
- ChatGPT and dots: At chatgpt.com/plugins, choose + and Add custom MCP server, paste https://mcp.auto.dev/mcp and choose OAuth, then Create as a plugin. Your dot uses the same plugin

Or install the `auto` CLI, the local MCP server (`auto --mcp`) and the JavaScript SDK in one package:

```sh
npm install -g @auto.dev/sdk
auto login
auto mcp install
```

- Agent skill: `npx skills add drivly/auto-dev-skill`

This API is the `auto_apr` MCP tool. From the terminal: `auto apr 1C4HJXEN5MW592818 --year 2021 --make Jeep --model Wrangler --zip 37129 --credit-score 720 --vehicle-age 3 --vehicle-mileage 36000`

## Questions

### What does the Interest Rates API return?

APR by term, 36 to 84 months, credit score used, ZIP code, vehicle age and mileage. Every response is JSON from `https://api.auto.dev/apr/{vin}`.

### How much does the Interest Rates API cost?

Interest Rates is available from the Growth plan. It costs $0.005 per call on Growth and $0.004 per call on Scale, on top of the plan's subscription.

### How do I call the Interest Rates API?

Send `GET /apr/{vin}` to `api.auto.dev` with your API key as a Bearer token in the `Authorization` header, or as an `apiKey` query parameter. The path takes `vin`, the 17-character Vehicle Identification Number (letters and digits, excluding I, O, and Q). Required query parameters: `year`, `make`, `model`, `zip`, `creditScore`.

### What are the rate limits for Interest Rates?

Rate limits follow your plan: 5 requests per second on Free, 10 on Growth and 50 on Scale. Interest Rates needs Growth or above.

### Can AI agents use the Interest Rates API?

Yes. Connect the hosted MCP server, `https://mcp.auto.dev/mcp`, and agents such as Claude Code and Cursor call it as the `auto_apr` tool, signing in with OAuth instead of an API key. Or run it locally: `npm install -g @auto.dev/sdk`, then `auto login` and `auto mcp install`.

## Related APIs

- [Vehicle Payments](https://www.auto.dev/vehicle-payments.md): Calculate monthly payments, financing options, and payment estimates.
- [Taxes & Fees](https://www.auto.dev/taxes-fees.md): Registration fees, taxes, and location-specific vehicle costs.
- [Total Cost of Ownership](https://www.auto.dev/total-cost-ownership.md): Comprehensive ownership costs including depreciation, maintenance, and operating expenses.

## References

- Docs: https://docs.auto.dev/v2/products/interest-rates
- OpenAPI: https://www.auto.dev/openapi.json (JSON), https://www.auto.dev/openapi.yaml (YAML)
- llms.txt: https://www.auto.dev/llms.txt
- Pricing: https://www.auto.dev/pricing
- Sign up: https://www.auto.dev/signin?redirectUrl=%2Fonboarding