This page may contain stale information. Last updated: 2026-07-02
Definition
x402 is an open HTTP payment protocol developed by Coinbase that revives the HTTP 402 Payment Required status code to enable instant, programmatic stablecoin payments — designed for both human developers and AI agents without accounts, sessions, or manual checkout.
Key Points
- Flow: Server returns 402 with
PAYMENT-REQUIREDheader → client sendsPAYMENT-SIGNATURE→ facilitator verifies/settles onchain - Networks: Base, Polygon, Arbitrum, World, Solana via CDP facilitator (1,000 free tx/month)
- Tokens: USDC/EURC via EIP-3009; any ERC-20 via Permit2
- Adoption (June 2026): 100M+ transactions since May 2025 launch; ~157K agent buyers in past 30 days (x402scan.com); millions of agent-ecosystem transactions
- 2026-06-24: Platform-wide agentic checkout on all Coinbase Payments APIs; Bedrock AgentCore integration; facilitator pricing $0.001/tx after 1,000 free/month
- MCP integration:
@coinbase/payments-mcpconnects ChatGPT, Claude, Codex CLI to x402 wallets - P3P integration: pine-labs p3p-protocol uses HTTP 402 for machine-readable agent payment challenges in India UPI flows
- 2026-07-01: cloudflare Monetization Gateway (waitlist) — edge payment verification for APIs, MCP tools, web pages; USDC + Open USD settlement (2026-07-02-cloudflare-monetization-gateway-official)
- Ecosystem: x402 Foundation with 25+ industry leaders; Visa, Stripe among participants
Use Cases
- Per-request API monetization
- AI agents paying for data APIs, compute, paywalled research
- Microtransactions and usage-based billing
- Machine-to-machine commerce underpinning agentic-commerce
Related
- coinbase
- stablecoin
- model-context-protocol
- agentic-ai-payments
- payment-infrastructure
- p3p-protocol
- cryptocurrency