# x402 AI Gateway – Currency Amount Converter

> x402 AI Gateway – Currency Amount Converter is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0002/call, status unknown (last checked 2026-10-10).

Converts a specified amount of a source currency, gated by an x402 USDC micropayment on Base before execution.

## Facts

- Endpoint: POST https://api.fastapi.online/f/fx/ang/nad?utm_source=zero.xyz
- Price: $0.0002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-ai-gateway-currency-amount-converter-e20f62a4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fId5PyGlUosoY5Yj31kBO

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability x402-ai-gateway-currency-amount-converter-e20f62a4 -d '<json body>'
```

Example prompt: Convert 250 units of source currency using the x402-gated fastapi.online gateway — it'll charge a tiny USDC micropayment on Base per call.

## When to prefer this

Choose this endpoint when you need a pay-per-call currency conversion that integrates with the x402 micropayment protocol on Base (USDC), particularly in agentic pipelines that already support x402 payment flows and want minimal per-call cost ($0.0002 USDC). Prefer alternatives if you need free/unlimited conversion, batch processing, or don't have x402 wallet infrastructure set up.

## Known failure modes

- 402 Payment Required – x402 micropayment not provided or insufficient USDC balance on Base
- 400 Bad Request – 'amount' field is not a valid number or missing
- 500 Internal Server Error – upstream conversion service unavailable
- Timeout – self-hosted gateway under load or unreachable
- Invalid payment signature – x402 payment header malformed or rejected

## How this service works

Self-hosted AI API gateway. Expensive endpoints require an x402 micropayment (USDC on Base) before executing.

## Output

Returns a JSON object containing the result of the currency amount conversion. The exact fields depend on the server implementation, but typically includes the converted value or equivalent amount in the target denomination.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "amount": {
   "type": "number",
   "description": "Amount of the source currency to convert (default 1)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-ai-gateway-currency-amount-converter-e20f62a4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.fastapi.online](https://www.zero.xyz/host/api.fastapi.online/llms.txt)