# numberintel.dev x402 Settlement Attestation

> numberintel.dev x402 Settlement Attestation is a paid API for AI agents from numberintel.dev, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-02).

Acts as an x402 payment proxy that purchases a target API endpoint on the caller's behalf and returns a cryptographically signed attestation of delivery, settlement, and response quality.

## Facts

- Endpoint: POST https://numberintel.dev/v1/attest?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/numberintel-dev-x402-settlement-attestation-f0f5deca
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_03PPOYtxuzvyd8fFAE3fY

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 numberintel-dev-x402-settlement-attestation-f0f5deca -d '<json body>'
```

Example prompt: Call the x402 phone intelligence endpoint at https://numberintel.dev/v1/lookup for me, cap the spend at $0.05, and bring back a signed attestation proving it was paid and delivered correctly.

## When to prefer this

Choose this endpoint when you need a cryptographically signed, on-chain proof that a specific x402 pay-per-call API was successfully purchased, called, and delivered a valid response. It is ideal for audit trails, agent-to-agent trust, or compliance scenarios where proving payment and delivery happened is as important as the data itself. Prefer it over raw x402 calls when the consumer needs an attestor-signed receipt rather than just the raw API response.

## Known failure modes

- Target URL unreachable or returns non-2xx before payment: attestation grade may reflect failure
- max_spend_usd exceeded by target price: call aborted before payment
- Invalid or non-x402 target URL: request rejected with error
- Insufficient USDC balance for x402 settlement: payment fails
- Target endpoint schema mismatch: low schema_match_ratio in attestation but call may still be graded delivered
- Network congestion on Base causing settlement delays

## How this service works

Signed settlement attestation: we make a REAL x402 purchase from your target endpoint (up to $0.1), grade the delivered response against its advertised schema, and return an EIP-191-signed attestation embedding the on-chain USDC receipt. Proof-of-real-delivery for directories, reputation systems and sellers.

## Output

Returns a JSON object containing a hex signature from the attestor, and a nested attestation object with: a unique attestation ID, a delivery grade (e.g. 'delivered'), the target URL, attestor address, delivery details (SHA-256 hash of response, is_json flag, HTTP status, paid latency in ms, schema match ratio), and purchase details including the on-chain transaction hash on Base (eip155:8453), settlement status, and the quoted USD cost.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "body": {
   "type": "object",
   "description": "JSON body for POST targets"
  },
  "method": {
   "type": "string",
   "description": "GET or POST"
  },
  "target": {
   "type": "string",
   "description": "https URL of the x402 endpoint to buy from"
  },
  "max_spend_usd": {
   "type": "number",
   "description": "cap on target spend, hard max 0.1"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "signature": "0x...",
  "attestation": {
   "id": "a1b2c3d4e5f60718",
   "grade": "delivered",
   "target": "https://api.example.com/v1/data",
   "version": 1,
   "attestor": "0x3708...9234",
   "delivery": {
    "sha256": "...",
    "is_json": true,
    "http_status": 200,
    "paid_latency_ms": 900,
    "schema_match_ratio": 1
   },
   "purchase": {
    "receipt": {
     "network": "eip155:8453",
     "transaction": "0x..."
    },
    "settled": true,
    "quote_usd": 0.01
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/numberintel-dev-x402-settlement-attestation-f0f5deca/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from numberintel.dev](https://www.zero.xyz/host/numberintel.dev/llms.txt)