x402 — A payment protocol built on HTTP's long-unused 402 status code, letting a server charge per request so software agents can pay without an account.
Why it matters
Vercel's Is Agentic audits now group checks by site type (docs, business, app, commerce), so a commerce site sees payment/checkout standards like x402A payment protocol built on HTTP's long-unused 402 status code, letting a server charge per request so software agents can pay without an account.Full definition → while an API surfaces auth and SDK checks, set via a single meta tag.
