Defined in early HTTP/1.1 drafts, status code 402 Payment Required was intentionally reserved for a future payment layer. The future looks like programmable, bearer-value handshakes where sats move as fast as packets.
RFC 7231 reserves 402 Payment Required for future use. Early HTTP notes imagined a status for resources that needed settlement before delivery - the spec never shipped concrete semantics, leaving the field open for a modern, interoperable payment rail.
Small, programmable payments unlock a layer of coordination that ads and subscriptions cannot. With headers describing price, accepted methods, and retry semantics, 402 can become the missing primitive for pay-per-call APIs, paid media, and AI inference workloads.
HTTP/1.1 402 Payment Required
Payment-Required: true
Payment-Method: bitcoin-lightning
Amount-Due: 21 sats
Retry-After: receipt
Calibrate price per request, pick your payment rail, and watch the request retried with a 200 OK once paid.