# QuantaFlow x402 API Gateway – Stack Exchange Proxy

> QuantaFlow x402 API Gateway – Stack Exchange Proxy is a paid API for AI agents from quanta-roan.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-14).

Proxies requests to the Stack Exchange API through an x402 micropayment gateway, charging $0.01 USDC per call

## Facts

- Endpoint: POST https://quanta-roan.vercel.app/api/service/stackexchange?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quantaflow-x402-api-gateway-stack-exchange-proxy-262b81dc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_H_1S2F6foTiYhSUYNc-Sr

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-stack-exchange-proxy-262b81dc -d '<json body>'
```

Example prompt: Search Stack Overflow for the top answers to 'how to handle async errors in JavaScript promises' and return the highest-voted responses.

## When to prefer this

Use this endpoint when you need programmatic access to Stack Exchange / Stack Overflow data and are operating in a web3 or x402-enabled agent environment where micropayments are acceptable. Prefer this over direct Stack Exchange API calls when you want a pay-per-use model without managing API keys, or when integrating into an x402 payment-enabled workflow.

## Known failure modes

- Payment failure if wallet lacks sufficient USDC balance — HTTP 402 returned
- Invalid or missing Stack Exchange API path — upstream 404 or 400 returned
- Malformed query parameters — upstream API may return error or empty results
- Rate limiting by Stack Exchange upstream — 429 passed through
- Stack Exchange API key quota exhausted — upstream error forwarded

## How this service works

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

## Output

The raw upstream Stack Exchange API response, including questions, answers, scores, tags, user info, and metadata, passed through directly after successful x402 micropayment verification.

## 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-stack-exchange-proxy-262b81dc/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)