# x402 AI Gateway – Currency Amount Conversion

> x402 AI Gateway – Currency Amount Conversion is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0002/call, status unknown (last checked 2026-10-12).

Converts a specified amount of a source currency, gated by a $0.0002 USDC x402 micropayment on Base before executing.

## Facts

- Endpoint: POST https://api.fastapi.online/f/fx/aoa/ves?utm_source=zero.xyz
- Price: $0.0002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-ai-gateway-currency-amount-conversion-c7f9d60d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1dWqACUhKBmQF-PJ5mG3J

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-conversion-c7f9d60d -d '<json body>'
```

Example prompt: Convert 250 units of the source currency using the x402 micropayment gateway — I'm okay paying the $0.0002 USDC fee per call on Base to get the result.

## When to prefer this

Choose this endpoint when you need a pay-per-call, self-hosted currency amount conversion that is gated by an x402 USDC micropayment on Base — ideal for agent workflows where on-chain payment authorization is required or preferred over API key subscriptions.

## Known failure modes

- Payment not included or insufficient USDC: 402 Payment Required response blocking execution
- Invalid or missing 'amount' field: request rejected or defaults to 1
- Backend conversion service unavailable: 5xx error returned
- Malformed x402 payment header: gateway rejects the request
- Amount is zero or negative: undefined or error result

## 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 conversion result for the specified amount; exact fields depend on the gateway's configured currency pair and backend logic.

## 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-conversion-c7f9d60d/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)