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numberintel.dev x402 Settlement Attestation
x402
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.
Price / call$0.25
Success—
StatusUnknown
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.
Example use cases
Audit trail for paid API calls
“I need a verifiable receipt proving that the x402 endpoint at https://api.example.com/v1/data was successfully called, paid in USDC, and returned a valid JSON response — cap the spend at $0.05 and give me the signed attestation.”
Agent-to-agent x402 payment verification
“My agent just attempted a pay-per-call to https://numberintel.dev/v1/lookup — can you proxy that call with a max spend of $0.10 and return a cryptographic attestation I can show to prove settlement happened on Base?”
Schema compliance check for paid API response
“Hit the x402 endpoint at https://data.example.com/v1/records with a POST and body {"query":"test"}, cap the spend at $0.08, and tell me the schema match ratio and delivery grade from the attestation.”
Technical details
Endpoint
POSThttps://numberintel.dev/v1/attest?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| body | object | JSON body for POST targets |
| method | string | GET or POST |
| target | string | https URL of the x402 endpoint to buy from |
| max_spend_usd | number | cap on target spend, hard max 0.1 |
Output
Schema · Response
{
"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
}
}
}
}Tags
x402
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