# QuantaFlow x402 API Gateway — Alchemy StarkNet Mainnet

> QuantaFlow x402 API Gateway — Alchemy StarkNet Mainnet is a paid API for AI agents from quanta-roan.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-17).

Proxies requests to the Alchemy StarkNet Mainnet RPC/API through an x402 micropayment-gated gateway, charging $0.01 USDC per call.

## Facts

- Endpoint: POST https://quanta-roan.vercel.app/api/service/alchemy-starknet-mainnet?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quantaflow-x402-api-gateway-alchemy-starknet-mainnet-3a9ec213
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4z8mZ1_D8sjiN533iXena

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-starknet-mainnet-3a9ec213 -d '<json body>'
```

Example prompt: Look up the latest block on StarkNet mainnet using Alchemy — I need the block hash and timestamp for block number 500000.

## When to prefer this

Choose this endpoint when you need pay-per-call access to Alchemy's StarkNet Mainnet RPC without a subscription API key, using x402 USDC micropayments. Ideal for agents that need occasional or low-volume StarkNet data queries (block data, contract calls, transaction lookups) and want to pay only for what they use at $0.01 per call rather than maintaining an Alchemy account.

## Known failure modes

- Payment failure: insufficient USDC balance or x402 payment not accepted — gateway returns 402 Payment Required
- Invalid path: upstream Alchemy endpoint not found for the specified path — returns 404 or upstream error
- Malformed JSON body: invalid JSON in the body field causes upstream rejection
- RPC method error: StarkNet RPC returns an error (e.g. contract not found, invalid block number) passed through from Alchemy
- Rate limiting: Alchemy upstream rate limit exceeded — returns 429 or upstream throttle response
- Network timeout: StarkNet mainnet node unresponsive — gateway may return 504 or timeout error

## How this service works

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

## Output

The raw upstream response from Alchemy's StarkNet Mainnet API is passed through directly after successful x402 micropayment verification — including JSON-encoded blockchain data such as block info, transaction receipts, contract call results, or RPC method responses, along with the original content type.

## 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-starknet-mainnet-3a9ec213/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)