x402 facilitator

In x402 the resource server does not need to run a node or hold gas. It forwards the client's signed payment payload to a facilitator, which checks that the signature, amount and asset match the requirements, then submits the transfer to the chain and reports back. The server releases the response once the facilitator confirms settlement.

Because the facilitator is the party that broadcasts, it is also the party whose key appears on-chain as the transaction sender. That is how Sato Hub attributes settlement to a facilitator: by the key that settled, not by whose logo is on the site. Coinbase's Developer Platform runs the most widely used facilitator; others exist, and a server can run its own.

A facilitator is a convenience, not an authority. It does not custody funds for either side, it does not vouch for the resource being paid for, and it cannot make a payment succeed that the payer did not sign.