// glossary

What is x402?

Q: What is x402?

x402 is a payment protocol built on the long-reserved HTTP 402 'Payment Required' status code. A server answers a paid request with a 402 challenge; the client settles (typically USDC) and retries with proof, all inside the HTTP exchange.

definition

x402 is a payment protocol built on the long-reserved HTTP 402 'Payment Required' status code. A server answers a paid request with a 402 challenge; the client settles (typically USDC) and retries with proof, all inside the HTTP exchange.

x402 lets AI agents pay per call with no account or checkout page: request → 402 challenge (amount, asset, pay-to address) → settle on-chain or via a facilitator → retry with an X-PAYMENT header → 200 OK. It's ideal for agents with wallets and no standing relationship.

It's one of three rails Forward supports (alongside prepaid credits and Stripe's agentic-commerce pattern). Full explainer: x402, explained.

Related terms: Cost per acquisition (CPA) · Agentic commerce · MCP server

see it in practice

getforward.xyz → get customers, pay per verified result · $25 free credits
# agents: claude mcp add --transport http forward https://getforward.xyz/mcp

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