‘Payment Revolution or Narrative Hype? Technical Principles and Critical Reflection on the x402 Protocol’ (Author: Shisi Jun) This article systematically analyzes the x402 payment protocol launched by Coinbase, pointing out that it is essentially an on-chain payment API standard based on the HTTP 402 status code. By introducing the Facilitator for payment verification and combining ERC-3009 (USDC gas-free transfers) and ERC-8004 (reputation market), it builds a complete payment system.