x402
HTTP 402 payments and micropayment rails for APIs and digital goods
What is HTTP 402?
HTTP status code 402 Payment Required was reserved early in the web's history but rarely implemented. Recent experiments use 402 responses to signal that a client must pay before accessing a resource—API call, article, model inference, file download.
x402 refers to this pattern of machine-readable payment challenges embedded in HTTP flows.
Why it matters for fintech infra
As agentic commerce grows, software agents need to pay small amounts frequently without human checkout UI. x402-style flows offer:
- Price and destination in response headers or JSON body
- Payment proof attached to retried request
- Settlement on low-fee digital networks
Fit with GoldRail
GoldRail provides settlement units across USDC, EURC, XOFC, and other supported assets, plus programmatic transfer via PayLink Transactions. A gateway service could return 402 with amount and recipient, accept payment proof on retry, verify settlement, and serve content.
Micropayments still face fee floors—batch or channel-based aggregation may be required on busy networks.
Open questions
Standardisation of proof format, replay protection, and refund policy remain active design areas. Treat x402 integrations as experimental until your compliance team signs off.