# x402 AI Gateway – Currency Conversion

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

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/aoa/xsu?utm_source=zero.xyz
- Price: $0.0002/call
- Payment: x402
- Status: down
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-ai-gateway-currency-conversion-0a345b81
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_dhL27scRLdRkZZivK52_4

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-conversion-0a345b81 -d '<json body>'
```

Example prompt: Convert 250 units of the source currency using the x402 AI gateway — it costs a tiny USDC micropayment per call.

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call currency conversion without subscription overhead, and you already have an x402-compatible USDC wallet on Base. It is ideal for low-frequency automated agents that want to avoid API key management and prefer crypto micropayments. Not ideal if you need high-volume batch conversions or guaranteed SLAs from a commercial FX provider.

## Known failure modes

- Payment not provided or rejected — HTTP 402 returned, requiring a valid USDC micropayment on Base before proceeding
- Invalid or missing amount field — server may return a 422 validation error
- Unsupported currency pair — endpoint may return an error if the source/target currency is not supported
- Server unavailable — self-hosted infrastructure may experience downtime or rate limiting
- Micropayment facilitator network issues — Base network congestion could delay or fail payment settlement

## How this service works

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

## Output

A JSON object containing the result of the currency conversion computation, returned after the x402 USDC micropayment on Base is settled. Exact fields depend on server implementation but typically include the converted amount and possibly the exchange rate used.

## 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-conversion-0a345b81/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)