Permanently certify what a public web page serves right now. Pays with x402 (USDC on Base): $1.00 for mode 'fullpage' (default, whole page) or $0.50 for mode 'viewport' (first 1280x800 screen). Two independent observers capture the URL at one frozen timestamp; matching captures are tier CERTIFIED, differing ones are WITNESSED (with pixel agreement percent and diff map). Evidence is stored permanently on Arweave and an ERC-721 certificate is minted on Base to the paying wallet. This tool polls the claim ticket for up to about 6 minutes (fulfillment is normally 30-120 seconds). If it times out, the returned claim_url is durable: fetch it later with a plain GET to collect the result. Rejected captures refund automatically minus a $0.10 fee; service faults refund in full.

Re-verify any exhibit402 certificate for $0.02 (x402, USDC on Base). Pass the certificate's ERC-721 token id (digits), its Arweave manifest tx id (43 chars), or the exhibit402 job id (uuid). The service re-downloads the permanently stored screenshot and signed manifest, recomputes every SHA-256 from the actual bytes, and compares against the manifest and the on-chain record. Returns a machine-readable verdict: verified true/false plus per-check results (manifest_resolves, screenshot_hash, observer_agreement, onchain_sha256, rfc3161_timestamp). A false verdict is a delivered result and is charged; malformed ids, unknown ids, and gateway outages are not charged.