x402

The x402 protocol enables HTTP-native payments by returning a 402 Payment Required status with a structured JSON header specifying token, amount, and recipient address. Clients (human or autonomous agent) settle the payment on-chain and replay the request with a signed receipt. Coinbase co-authored the open standard (March 2026); the x402 Foundation co-stewarded by Cloudflare governs the specification.

Canonical site: Stable402.com Cross-references: StableM2M.com, StableIAM.com