# 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 2026-10-11).

Converts a specified amount of a source currency via a self-hosted AI gateway endpoint protected by x402 USDC micropayment.

## Facts

- Endpoint: POST https://api.fastapi.online/f/fx/ang/pab?utm_source=zero.xyz
- Price: $0.0002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-ai-gateway-currency-amount-conversion-da951bb5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vOeqIQtZuNGwaxDIfT9h0

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-da951bb5 -d '<json body>'
```

Example prompt: Convert 250 units of my source currency using the x402 micropayment gateway — go ahead and authorize the $0.0002 USDC payment on Base to get the result.

## When to prefer this

Choose this endpoint when you need a pay-per-call currency conversion that settles instantly via USDC micropayment on Base, especially in autonomous agent workflows where on-chain payment authorization is already set up. Prefer it over free or subscription-based APIs when you want minimal commitment and true usage-based billing at $0.0002 per call. Avoid if you need a well-documented schema, guaranteed uptime SLA, or do not have a USDC wallet configured on Base.

## Known failure modes

- Payment not authorized or insufficient USDC balance on Base — returns HTTP 402 Payment Required
- Invalid or missing 'amount' field — may return a 4xx validation error
- Gateway server unavailable or self-hosted instance down — returns 5xx or connection timeout
- x402 facilitator unable to verify payment — transaction rejected before processing
- Amount value out of supported range — unspecified error response

## 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 conversion computation. The exact fields are not documented in the schema beyond a generic object, so the agent should inspect the response body for the converted value and any metadata returned by the gateway.

## 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-da951bb5/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)