# QuantaFlow Exchange Rate API (x402)

> QuantaFlow Exchange Rate API (x402) is a paid API for AI agents from quanta-roan.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Fetches cryptocurrency or fiat exchange rate data via a pay-per-call x402 micropayment gateway, charging $0.01 USDC per request.

## Facts

- Endpoint: POST https://quanta-roan.vercel.app/api/service/exchangerate?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quantaflow-exchange-rate-api-x402-f75e96cc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7IIafSvNmCBS9IFSEf7eA

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 quantaflow-exchange-rate-api-x402-f75e96cc -d '<json body>'
```

Example prompt: What's the current exchange rate between ETH and USDC right now? Use the QuantaFlow exchange rate service to get me a live quote.

## When to prefer this

Choose this endpoint when you need real-time exchange rate or cryptocurrency price data and are operating in a web3/DeFi context where micropayment-based access ($0.01 USDC per call) via the x402 protocol is acceptable. It is particularly suited for AI agents that already hold USDC and need lightweight, pay-as-you-go access without API key management. Prefer it over free-tier REST APIs when you want deterministic per-call billing with no subscription overhead.

## Known failure modes

- Payment failure: insufficient USDC balance or x402 payment not accepted — returns 402 Payment Required
- Invalid path or query: upstream exchange rate service returns 400 or 404 if the currency pair is not found
- Upstream service unavailable: 502 or 503 if the underlying exchange rate provider is down
- Malformed request body: upstream rejects the forwarded JSON body if improperly structured
- Rate limiting: upstream provider throttles requests even after payment is accepted

## How this service works

Every request, a quantum of value. x402 protocol-based payment endpoint for web3/DeFi tools.

## Output

Returns the upstream exchange rate data as a pass-through response body (JSON), including the rate or price for the requested currency pair, along with the content type from the upstream provider. The exact schema depends on the upstream exchange rate service being proxied.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "body": {
   "type": "string",
   "description": "Optional JSON body forwarded to POST requests."
  },
  "path": {
   "type": "string",
   "description": "Path below the selected upstream origin."
  },
  "query": {
   "type": "object"
  },
  "method": {
   "enum": [
    "GET",
    "POST"
   ],
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "description": "The upstream response body and content type are passed through after successful payment."
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quantaflow-exchange-rate-api-x402-f75e96cc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from quanta-roan.vercel.app](https://www.zero.xyz/host/quanta-roan.vercel.app/llms.txt)