x402 Overview
x402 is an open payment protocol developed by Coinbase that enables instant, automatic stablecoin payments directly over HTTP by reviving the HTTP 402 Payment Required status code.
The x402 Facilitator handles payment verification and settlement so sellers don’t need to maintain their own blockchain infrastructure. The Coinbase Developer Platform offers a hosted facilitator service processing ERC-20 payments on Base, Polygon, Arbitrum, World, and Solana with 1,000 free transactions per month, then $0.001/transaction.
On June 24, 2026, Coinbase expanded agentic checkout to all Payments APIs, enabling AI agents to autonomously complete stablecoin transactions via x402 on Base. Transaction costs are under $0.001. The rollout integrates with Amazon Bedrock AgentCore Payments. Agents can pay per API call without accounts or API keys when servers return HTTP 402 responses.
Coinbase holds 80+ global licenses and reports millions of agent-ecosystem transactions.
Flow: (1) buyer requests resource; (2) server returns 402 with PAYMENT-REQUIRED header; (3) buyer sends PAYMENT-SIGNATURE header; (4) facilitator verifies and settles; server returns resource.