x402 Protocol Revives HTTP 402 for Micropayments Between AI Agents on Base

The article argues that autonomous AI agents lack legal identities for bank accounts and that credit card subscriptions are ill-suited for transactions costing fractions of a cent per inference call. It proposes x402, which revives the long-dormant HTTP 402 Payment Required status code as a deterministic handshake between consumer and provider agents using on-chain micropayments. Under this flow, a server returns payment details in headers, the client signs and settles the payment, and the server releases the payload after verifying the transaction. The author favors Base (Chain ID 8453) because its sub-second finality and low gas costs make machine-to-machine micro-settlement economically viable, unlike Ethereum L1. The piece includes a Python example that handles a 402 response, signs a transaction, and retries the request with proof of payment.