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Attest402 — Signed Evidence of Public Web/API Response
x402
Attest402 — Signed Evidence of Public Web/API Response is a paid API for AI agents from attest402.com, paid per call via x402, $0.2/call, status unknown (last checked 2026-10-12).
Fetches a public URL and returns cryptographically signed, timestamped evidence of the HTTP response — body hash, headers hash, HTTP status, and an Ed25519 attestation — payable per-call with x402 USDC.
Price / call$0.2
Success—
StatusUnknown
How this service works
Cryptographically signed and timestamped evidence of a public web or API response. Pay per call with x402 (0.20 USDC on Base). No account, no API key. Built for AI agents.
Output
A JSON object containing: the requested and final URLs, HTTP status code, content type and length, a SHA-256 hash of the response body and headers, the timestamp of observation, a redirect chain, an Ed25519 digital signature with key ID and algorithm, a canonical record hash, a schema version, a trusted RFC3161 timestamp token hash and status, a unique attestation ID, a public verification URL, and a URL to download the full evidence package.
Example use cases
Price feed proof for smart contract
“Grab https://api.coinbase.com/v2/prices/ETH-USD/spot and generate a signed, timestamped attestation of the response so I can submit cryptographic proof of the ETH price to my on-chain contract.”
Compliance snapshot of public record
“Attest the current content of https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0001018724&type=10-K — I need a tamper-evident, RFC3161-timestamped evidence package I can attach to our audit file.”
Dispute resolution for web content
“I need a cryptographically signed snapshot of https://example.com/terms-of-service as it exists right now — with a body hash, headers hash, and a verification URL — so I have legally defensible proof of what the page said today.”
Technical details
Endpoint
POSThttps://attest402.com/v1/attest?utm_source=zero.xyzWhen to prefer
Choose Attest402 when you need cryptographically verifiable, independently auditable proof of what a public URL returned at a specific moment — especially for smart contract oracles, legal/compliance evidence, dispute resolution, or any workflow where trusting a screenshot or log is insufficient. Prefer it over simple HTTP fetching when tamper-evidence, a trusted RFC3161 timestamp, and a public verification link are required. It is purpose-built for AI agents via x402 pay-per-call with no account setup.
Side effects
- Non-public or authenticated URLs will fail or return incomplete evidence
- Target URL returns non-200 status — attestation still issued but records actual HTTP status
- Payment not received or x402 flow fails — request not processed
- Target URL unreachable or times out — no attestation issued
- Invalid or malformed URL input — request rejected
- Target server returns unexpected content type or very large body — may affect processing
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Public HTTPS URL to capture (GET only, max 2 MB, max 3 redirects). |
| externalReference | string | Optional caller-side correlation id, embedded in the signed record. |
| includeTrustedTimestamp | boolean | Also anchor the record with an independent RFC-3161 timestamp. |
Output
Schema · Response
{
"type": "json",
"example": {
"bodyHash": "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
"finalUrl": "https://api.example.com/prices/btc",
"httpStatus": 200,
"observedAt": "2026-08-01T19:50:00.123Z",
"attestation": {
"keyId": "attest-prod-2026-01",
"algorithm": "Ed25519",
"signature": "base64:...",
"schemaVersion": "1.0",
"canonicalRecordHash": "sha256:..."
},
"contentType": "application/json",
"headersHash": "sha256:98fdc32...",
"requestedUrl": "https://api.example.com/prices/btc",
"attestationId": "attest_9f8a1b2c3d4e",
"contentLength": 4281,
"redirectChain": [],
"verificationUrl": "https://attest402.com/v1/verify/attest_9f8a1b2c3d4e",
"trustedTimestamp": {
"type": "RFC3161",
"status": "VALID",
"tokenHash": "sha256:..."
},
"evidencePackageUrl": "https://attest402.com/v1/evidence/attest_9f8a1b2c3d4e"
}
}Tags
x402
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