httppayaithirdweb

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

Canonicalize JSON before you hash, compare or sign it: one POST takes a JSON string or any JSON value and returns the RFC 8785 (JCS) form, its SHA-256 and its UTF-8 byte length. Object keys are ordered by UTF-16 code units, strings use minimal escaping, numbers use ECMAScript Number::toString, and arrays keep their order. Duplicate keys, NaN, Infinity, trailing commas and a lone surrogate are refused with 400 before any payment; integers outside +-2^53 come back with a number_precision_loss warning instead of being silently rounded. input_sha256 is the hash of the json as supplied, so it differs from sha256 when only whitespace or key order changed. The value is not stored, no URL is fetched and nothing is signed or transferred. curl: POST /json-canonical -H 'content-type: application/json' -d '{"json":"{\"b\":2,\"a\":1}"}' . Response: {canonical, sha256, bytes, input_sha256, warnings[], canonicalization, limits, paid, delivery}. No keys, no account, one POST, one delivery - 0.002 USDC. 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.