The refusal
A real 402
An unpaid request gets a genuine HTTP 402 carrying machine-readable terms: the price, the asset, the network, and where to pay. A paywall a machine can read.
A machine paywall, live
A price oracle machines pay per request.
No API keys, no accounts, no subscriptions. A client calls the API, gets an HTTP 402 with machine-readable payment terms, pays a fraction of a cent in USDC on Solana, retries, and gets the data. That protocol is x402.
Why this matters
Machine-to-machine commerce, working today.
x402 is Coinbase's open revival of HTTP 402 Payment Required. It lets a machine pay for exactly what it uses, per request, with no sign-up flow. This oracle sells live price data that way, and buys its own upstream data the same way. Payment in both directions, settled on-chain.
The payment
A fraction of a cent
The caller pays $0.005 in USDC on Solana and retries with proof. The facilitator sponsors network fees, so a machine buyer holds only the USDC it spends, zero SOL.
The guarantee
Only pay for answers
Payment settles only after a successful response. Any refusal cancels it. You are never charged for an answer you did not get.