# QuantaFlow x402 API Gateway – Alchemy Stable Testnet

> QuantaFlow x402 API Gateway – Alchemy Stable Testnet is a paid API for AI agents from quanta-roan.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-18).

Proxies requests to Alchemy's stable testnet APIs via an x402 micropayment-gated gateway, forwarding arbitrary paths, query params, and request bodies to the upstream Alchemy service.

## Facts

- Endpoint: POST https://quanta-roan.vercel.app/api/service/alchemy-stable-testnet?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quantaflow-x402-api-gateway-alchemy-stable-testnet-b7399379
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_OIHJUCithCRkxSaXUhvZ2

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-x402-api-gateway-alchemy-stable-testnet-b7399379 -d '<json body>'
```

Example prompt: Call the Alchemy stable testnet API at path '/v2/eth_getBalance' with query param 'address=0xABC123' — route it through QuantaFlow and pay the $0.01 USDC x402 fee automatically.

## When to prefer this

Choose this endpoint when you need pay-per-call access to Alchemy's stable testnet APIs without committing to a subscription plan, or when operating in a web3/DeFi agent context where x402 micropayments are the preferred payment mechanism. Ideal for low-frequency or automated testnet queries where per-request USDC billing is more efficient than a monthly API key.

## Known failure modes

- Payment verification failure if insufficient USDC balance or invalid x402 header — gateway returns 402 Payment Required
- Invalid or unsupported path results in upstream 404 from Alchemy
- Malformed JSON body causes upstream 400 Bad Request passed through
- Alchemy rate limits or API key exhaustion may return 429 upstream
- Testnet instability or Alchemy downtime results in 502/503 passthrough errors
- Missing required 'path' parameter results in gateway-level error

## How this service works

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

## Output

The raw upstream Alchemy stable testnet API response body is passed through as-is, along with the original content type. The agent receives whatever JSON or data the Alchemy endpoint returns after the x402 payment is verified and the request is forwarded.

## 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-x402-api-gateway-alchemy-stable-testnet-b7399379/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)