# x402 AI Gateway – Currency Amount Conversion Endpoint

> x402 AI Gateway – Currency Amount Conversion Endpoint 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).

Accepts an amount of a source currency and returns a converted value, gated behind an x402 USDC micropayment on Base.

## Facts

- Endpoint: POST https://api.fastapi.online/f/fx/ang/fkp?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-endpoint-c64cd843
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2OTTRMUF5NXb1WyfASdSa

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-endpoint-c64cd843 -d '<json body>'
```

Example prompt: Convert 250 units of the source currency using the x402 AI gateway — pay the $0.0002 USDC micropayment and return the converted result.

## When to prefer this

Choose this endpoint when you need a per-call, micropayment-gated currency amount conversion without committing to a subscription, and you already have a USDC wallet on Base capable of x402 payments. It is appropriate for agents that want pay-as-you-go access to a self-hosted AI gateway with transparent per-call pricing.

## Known failure modes

- Payment not attached or insufficient USDC balance — returns HTTP 402 with payment instructions
- Invalid or missing 'amount' field — returns validation error
- Upstream inference or conversion service unavailable — returns 5xx error
- Network timeout if the self-hosted gateway is under load
- Incorrect Base network configuration causing payment failure

## 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 after the x402 micropayment (0.0002 USDC on Base) is verified and processed. The exact fields in the response are not documented in the schema but are expected to include the converted value.

## 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-endpoint-c64cd843/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)