x402: what it is, and what x402-ready means

What x402 is

HTTP has carried a reserved status code, 402 Payment Required, since the earliest version of the spec, unused for decades. x402 is the standard that finally gives it a job: a server responds 402 with machine-readable payment terms, a client (increasingly an AI agent acting on someone's behalf) settles the payment, and the request is retried and served. No checkout page, no human filling out a card form, no API key provisioned in advance. An agent that needs a paid API call, a piece of gated content, or a single product can pay for exactly that, in the same request.

It is early. It is also real: 169M+ agent payments have settled through x402 in its first year (Coinbase). That is the traction signal we track, not a projection.

What x402-ready means for a site

The x402 check in verified.md's scanner probes three signals: whether a metered API route actually returns 402 with an X-Payment header describing the scheme, whether agents.md mentions x402 support explicitly, and whether either signal is present at all. Passing does not require a fully wired settlement flow today, since the standard itself is still moving; it requires that a site has started declaring intent in a place an agent (or verified.md's own scanner) can find it.

This is the lightest-weight check in the whole scan, worth 2 of the 110 total weight points, because it is explicitly forward-looking: early support signals a site is building for where agent-native payments are going, not that it has already fully arrived.

What we implement

• 402 Payment Required responses with an X-Payment header on your metered API routes
• Explicit x402 support language in your agents.md, so agents and scanners can find the intent even before a route is wired
• A path to real settlement on the routes that make sense for your business (a paid API, gated content, a single-item purchase) once you are ready to move past signaling

See it live

verified.md's own /api/premium route is an early x402 stub: it returns 402 with an X-Payment header today, ahead of full settlement, the same starting point we recommend for most sites. /agents.md states the intent in plain language too.