What is an x402 facilitator?
A facilitator is the service that turns a signed x402 payment into a real one. When a caller pays for an API request, the API hands the signed payment to a facilitator. The facilitator checks it and submits it to the blockchain, then tells the API it went through.
The official x402 documentation at x402.org describes the facilitator's two jobs as verify and settle.
Why sellers use one
Without a facilitator, every API that wanted to take x402 payments would need its own connection to the blockchain, its own wallet to pay transaction fees and its own code to check signatures. A facilitator does all of that for many sellers at once. The seller adds a few lines of middleware and points it at a facilitator.
What a facilitator does not do
In the common setup on Base, the payment goes straight from the caller's wallet to the seller's wallet. The facilitator submits the transaction and usually pays its small network fee, but it never holds the money.
Who runs them
Coinbase runs the most widely used one. There are dozens of others, run by payment companies, infrastructure providers and open-source projects. Public dashboards such as x402scan list them and how much each one settles.
How Solvent uses this
Every facilitator submits payments from wallets it controls, and those wallets are public. Solvent's live demo uses a published list of known facilitator wallets to tell x402 payments apart from ordinary transfers, and shows which facilitator settled each one.