# Attest402

> Cryptographically signed and timestamped evidence of a public web or API response.
> Pay-per-call via x402 (0.20 USDC on Base). No account, no API key.

Attest402 is an agent-native attestation service. Send a public HTTPS URL; the service
fetches it, hashes body/headers/redirects, signs the record with Ed25519, anchors it with
an independent RFC-3161 timestamp and returns a portable evidence package that verifies
fully offline. Use it to prove what an API returned, timestamp a webpage, or preserve a
web response for an audit log.

The evidence confirms the integrity of the captured data and Attest402's observation at
the stated time. It does not certify the truth, legality or authorship of the content.

## API
- [OpenAPI spec](https://attest402.com/openapi.json): full machine-readable API description
- POST https://attest402.com/v1/attest — create an evidence package (x402, 0.20 USDC, Base).
  JSON body: {"url": "<public https url>", "externalReference": "<optional, <=100 chars>", "includeTrustedTimestamp": true}
- POST https://attest402.com/v1/verify — free verification of an attestation (+ optional bodyBase64)
- GET https://attest402.com/v1/verify/{attestationId} — free attestation metadata lookup
- GET https://attest402.com/v1/evidence/{attestationId} — download evidence package (zip, 24 h retention)
- GET https://attest402.com/.well-known/attest-keys.json — Ed25519 public keys (old keys stay available)
- GET https://attest402.com/.well-known/x402.json — x402 discovery manifest

## Payment (x402)
- Scheme: exact, Asset: USDC, Network: Base, Price: 0.20 USDC per attestation
- The route answers HTTP 402 with payment requirements; pay with any x402 client
  (x402-fetch, x402 Python SDK, ...). Settlement only happens after a successful capture.

## Limits
- GET only, public HTTPS URLs only, port 443 only, max 3 redirects, max 2 MB response,
  10 s timeout. No login-protected content, no cookies, no JS rendering, no screenshots.
- Evidence packages are retained 24 hours; attestation metadata 90 days. Store the
  evidence package yourself for long-term custody.