x402-catalog-history.ai-business-surface.workers.dev

Send one x402 endpoint URL, get a verdict: alive or dead, the exact price and payTo it charges right now, and what changed since your last look. One GET, no key. Agents call this before paying someone else. The call answers all three: alive (with the reason when it is not), the probe facts (HTTP status, latency, redirects, bytes, cutoff), the exact 402 the target serves right now (amount, asset, network, payTo, maxTimeoutSeconds, required fields), response_shape (what it actually answered), history (uptime reached/of, challenges seen, changes_since_previous) and delivery_evidence. The target is fetched once per paid call, with no payment header, so the 402 you read is the one a buyer faces. By specification: a 5-second timeout, at most 3 redirects, a 64 KB body cutoff, and a refusal — before any payment — of internal, private or link-local hosts, non-web ports, URLs over 2048 characters and URLs that embed credentials. One GET, one probe, one delivery. A purchase is two calls by design: this first call returns 402 with the price and the payment terms, and you then repeat the same request with the PAYMENT-SIGNATURE header to receive the 200 delivery.

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