# x402 Trust Attestation API

> x402 Trust Attestation API is a paid API for AI agents from x402-url-evidence.vercel.app, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-15).

Validates and attests the trustworthiness of an x402 payment-gated HTTPS endpoint by checking its protocol readiness, payment terms, and fingerprint integrity.

## Facts

- Endpoint: POST https://x402-url-evidence.vercel.app/api/x402-trust-attestation
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-trust-attestation-api-397444f8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_BS41n1PRuX0NSgw9N0VB9

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 x402-trust-attestation-api-397444f8 -d '<json body>'
```

Example prompt: Before we pay into that x402 endpoint at https://api.example.com/data, can you run a trust attestation on it — POST method, expecting USDC on Base sent to 0xAbC...123 — and tell me if it's safe to pay and whether the terms have changed from our last fingerprint 'a1b2c3...deadbeef'?

## When to prefer this

Use this endpoint when an AI agent needs to verify the integrity and payment parameters of an x402-gated API before committing USDC. It is the right choice when you want a deterministic, reproducible fingerprint of an endpoint's payment terms, when you need to detect drift between two calls (e.g. was the payTo address swapped?), or when onboarding a new third-party x402 service and need a safety audit. Prefer this over manual inspection when trust verification needs to be automated, auditable, and settled without human review.

## Known failure modes

- Endpoint URL is not reachable or returns non-x402 headers — verdict will indicate not ready
- Payment terms mismatch expected values (wrong asset, payTo, or network) — warnings or failures in summary
- Receipt transaction hash does not match current payment terms — attestation flags discrepancy
- Baseline fingerprint differs from current state — 'changed: true' returned, safeToPay may be false
- Malformed or non-HTTPS URL provided — validation error on input schema
- x402 protocol version incompatibility — protocol.ready returns false

## How this service works

Paid deterministic utility APIs settled in native USDC on Base.

## Output

Returns a JSON object containing: a boolean 'safeToPay' flag, a 'verdict' string (e.g. 'ready'), a 'protocol' object with x402 version and readiness, an 'attestation' object with SHA-256 fingerprint and a 'changed' boolean indicating drift from a prior baseline, a summary of passed/failed/warning checks, and an optional 'receipt' for transaction hash verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Credential-free public HTTPS x402 endpoint"
  },
  "method": {
   "enum": [
    "GET",
    "POST"
   ],
   "type": "string"
  },
  "expected": {
   "type": "object",
   "properties": {
    "asset": {
     "type": "string",
     "description": "Expected token contract"
    },
    "payTo": {
     "type": "string",
     "description": "Expected recipient address"
    },
    "network": {
     "type": "string",
     "description": "Expected CAIP-2 network"
    },
    "maxAmount": {
     "type": "string",
     "description": "Maximum accepted integer base-unit amount"
    }
   }
  },
  "receiptTxHash": {
   "type": "string",
   "description": "Optional Base transaction hash to verify against current terms"
  },
  "baselineFingerprint": {
   "type": "string",
   "description": "Optional prior SHA-256 attestation fingerprint"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "receipt": null,
  "summary": {
   "failed": 0,
   "passed": 15,
   "warnings": 0
  },
  "verdict": "ready",
  "protocol": {
   "ready": true,
   "x402Version": 2
  },
  "safeToPay": true,
  "attestation": {
   "changed": false,
   "algorithm": "sha256",
   "fingerprint": "64-character digest"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-trust-attestation-api-397444f8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-url-evidence.vercel.app](https://www.zero.xyz/host/x402-url-evidence.vercel.app/llms.txt)