# Roi Calculator — REST API endpoint `roi-calculator`

Return the return on investment: total invested (amount plus extra costs), net gain, simple ROI percent, annualized ROI percent, years to double at that rate (rule of 72), gain per year, and the percentage gain on the base amount alone.

- Category: finance
- MCP server: https://mcp.findutils.com/ (Streamable HTTP, API key for tools/call, 120 req/min per IP)
- REST endpoint: POST https://api.findutils.com/api/tools/roi-calculator/execute (API key, 60 req/min per IP)
- API key: Running a tool needs an API key. Keys are not for sale yet: ask for early access. Without a key, a tool call answers HTTP 402 Payment Required with the error code PAYMENT_REQUIRED. The catalog and the schemas stay open without a key. https://findutils.com/api/#api-keys
- Reference page: https://findutils.com/api/roi-calculator/
- Same tool on the other surface: https://findutils.com/mcp/roi-calculator/

## Call the endpoint (verified example)

```bash
curl -X POST https://api.findutils.com/api/tools/roi-calculator/execute \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "investment_amount": 10000,
    "final_value": 15000,
    "investment_years": 3,
    "additional_costs": 0
  }'

# Parameter schema (no key needed)
curl https://api.findutils.com/api/tools/roi-calculator
```

## Input schema

| Argument | Type | Required | Description |
|---|---|---|---|
| `investment_amount` | number | yes | Amount invested. Must be > 0. |
| `final_value` | number | yes | Value of the investment at the end. |
| `investment_years` | number | no | Holding period in years. Must be > 0. Default: 1. |
| `additional_costs` | number | no | Fees, taxes, or other costs added to the investment. Default: 0. |

Example arguments (verified):

```json
{
  "investment_amount": 10000,
  "final_value": 15000,
  "investment_years": 3,
  "additional_costs": 0
}
```

OpenAPI 3.1 spec: https://findutils.com/api/openapi.json · Interactive docs: https://findutils.com/api/docs/

## Also an MCP tool

```bash
claude mcp add findutils --transport http https://mcp.findutils.com/ --header "Authorization: Bearer YOUR_API_KEY"
```

Then ask the client to call `findutils:roi_calculator`. Full MCP reference: https://findutils.com/mcp/roi-calculator/

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