# Aether x402 Preflight Auditor

> Aether x402 Preflight Auditor is a paid API for AI agents from aether-x402.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-10).

Audits a public x402-gated endpoint to verify it is correctly configured and payable via USDC on Base, returning a scored verdict with pass/warn/fail checks.

## Facts

- Endpoint: POST https://aether-x402.vercel.app/api/x402/preflight?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/aether-x402-preflight-auditor-5a6f94d5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NM9vwYaGu42IIPVD8oyim

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 aether-x402-preflight-auditor-5a6f94d5 -d '<json body>'
```

Example prompt: Run a preflight audit on https://example.com/api/paid-endpoint — it's a POST endpoint that takes a JSON body like {"query": "test"} — and check whether it correctly accepts USDC payments on Base (eip155:8453) with a max price of $0.05.

## When to prefer this

Use this endpoint when you need to programmatically verify that an x402-gated API is correctly configured before attempting to pay and call it — especially useful for agents integrating new pay-per-call services, developers debugging their own x402 endpoints, or marketplace operators validating listed services. Prefer this over manual inspection when you need a structured, scored audit with actionable fix recommendations rather than raw HTTP inspection.

## Known failure modes

- Invalid or unreachable URL returns an error or low-score fail verdict
- payTo address with bad EIP-55 checksum triggers a fail check with fix guidance
- Endpoint does not support the expected asset or network, causing verdict fail
- Missing or malformed x402 payment headers on the target endpoint cause multiple fail checks
- Rate limiting or network timeouts if the target URL is slow to respond

## How this service works

Pay-per-call Base onchain data, token risk verdicts and x402 payability audits over x402 (USDC on Base).

## Output

Returns a JSON object with a numeric score (0-100), an array of individual checks each with a status (pass/warn/fail), a detail message, and a suggested fix, plus aggregated counts by status, a human-readable summary string, and an overall verdict of 'pass' or 'fail'.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048,
   "minLength": 1,
   "description": "Public https URL of the paid x402 endpoint to audit"
  },
  "body": {
   "description": "Example JSON body the endpoint accepts"
  },
  "expect": {
   "type": "object",
   "properties": {
    "asset": {
     "type": "string",
     "pattern": "^0x[0-9a-fA-F]{40}$"
    },
    "network": {
     "type": "string",
     "description": "CAIP-2 network, e.g. eip155:8453"
    },
    "maxPriceUsd": {
     "type": "number",
     "exclusiveMinimum": 0
    }
   },
   "description": "What the paying caller needs: fails the audit if the endpoint cannot be paid this way",
   "additionalProperties": false
  },
  "method": {
   "enum": [
    "GET",
    "POST",
    "PUT",
    "PATCH",
    "DELETE"
   ],
   "description": "Defaults to POST when body is supplied, otherwise GET"
  },
  "headers": {
   "type": "object",
   "description": "Non-credential headers the endpoint needs before its paywall (e.g. Idempotency-Key)",
   "maxProperties": 10,
   "additionalProperties": {
    "type": "string",
    "maxLength": 512
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "score": 67,
  "checks": [
   {
    "id": "accepts[0].payTo",
    "fix": "Copy the receiving address directly from your wallet; a bad checksum usually means a mistyped character.",
    "detail": "payTo has an invalid EIP-55 checksum (likely a typo)",
    "status": "fail"
   }
  ],
  "counts": {
   "fail": 1,
   "pass": 9,
   "warn": 1
  },
  "summary": "FAIL: 9 passed, 1 warning(s), 1 failure(s).",
  "verdict": "fail"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/aether-x402-preflight-auditor-5a6f94d5/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from aether-x402.vercel.app](https://www.zero.xyz/host/aether-x402.vercel.app/llms.txt)