What Is x402? How AI Agents Pay With Crypto
x402 is an open payment protocol that uses HTTP’s long-unused 402 response to let apps and AI agents pay for APIs and services, mainly in stablecoins such as USDC. Launched by Coinbase in 2025, it supports multiple blockchains and uses facilitators to verify and settle payments, enabling low-cost, automated transactions without subscriptions or API keys. The Linux Foundation now oversees the protocol through a vendor-neutral foundation, backed by major technology and payments firms. Reported usage exceeds 196 million transactions and $42 million in settlement, though much activity came from a short-lived token-trading surge; October 2026 volumes were far lower. x402 has no official token, and it competes with other emerging agent-payment standards. Its key test is whether transaction growth becomes sustained real commerce.
