{"glossary_note":"One entry per term. Each entry answers its own address as JSON.","glossary_rules":{"Sources":"Each entry is pinned to primary sources — a specification, an RFC, an EIP, or a party's own published documents — listed on the entry.","Numbers":"Entry text carries links rather than figures. Where a quantity matters, the entry links the source that holds it, so nothing here can go stale in silence.","Named parties":"A party is described as what it is and does, per its own documents. No ranking, no endorsement, and no comparison between parties."},"glossary":[{"slug":"facilitator","title":"facilitator","kind":"term","short":"A facilitator is a service that verifies and settles x402 payments on behalf of a seller. The seller's endpoint quotes a price, the buyer's client signs a payment authorization, and the facilitator checks that authorization against the quote and submits it to the blockchain.","path":"/glossary/facilitator"},{"slug":"payto","title":"payTo","kind":"term","short":"payTo is the field in an x402 payment quote that names the address a payment is sent to. It travels inside the HTTP 402 challenge, so it is chosen by whoever controls the endpoint at the moment of the quote, and it can differ between one request and the next.","path":"/glossary/payto"},{"slug":"catalogue","title":"catalogue","kind":"term","short":"A catalogue is a published list of x402 endpoints that a buyer or an agent can read to discover what is payable. Facilitators operate them, listing the endpoints that settle through the facilitator, so a listing is a curation decision rather than a property of the endpoint itself.","path":"/glossary/catalogue"},{"slug":"verify-and-settle","title":"verify and settle","kind":"term","short":"Verify and settle are the two operations an x402 facilitator exposes. Verify checks a signed payment payload against the quote the endpoint issued; settle submits that payload to the blockchain. They are separate calls, and a payload that passes verification has still moved no money.","path":"/glossary/verify-and-settle"},{"slug":"accepts-array","title":"accepts array","kind":"term","short":"The accepts array is the body of an x402 payment challenge: the list an endpoint returns with HTTP 402 when a request arrives unpaid. Each element of that array is one payment option the endpoint will take, stated in machine-readable terms.","path":"/glossary/accepts-array"},{"slug":"http-402","title":"HTTP 402","kind":"rail","short":"HTTP 402 is the response status code named Payment Required. RFC 9110 reserves it and defines no payment format, which leaves the meaning of such a response to whatever protocol is layered above it. x402 is one such protocol, and the status code is not the same thing as the protocol.","path":"/glossary/http-402"},{"slug":"settlement","title":"settlement","kind":"term","short":"Settlement is the step where an authorised x402 payment is submitted to the blockchain and the transfer actually happens. A quote, a signature and a successful verification all precede it, and none of them is a settlement.","path":"/glossary/settlement"},{"slug":"x402","title":"x402","kind":"rail","short":"x402 is an open protocol for paying for an HTTP request with a stablecoin transfer, using the HTTP 402 status code to carry the terms. It lets a client — often software rather than a person — pay per call, with no account, no key exchange and no subscription.","path":"/glossary/x402"},{"slug":"eip-3009","title":"EIP-3009","kind":"term","short":"EIP-3009 is an Ethereum token standard extension that lets a token holder sign a transfer authorization off-chain, which anyone can then submit on-chain. It is the mechanism under x402's exact scheme: the payer signs, and the facilitator pays the gas to submit.","path":"/glossary/eip-3009"},{"slug":"mpp","title":"MPP","kind":"rail","short":"MPP — the Machine Payments Protocol — is an open protocol for machine-to-machine payments over HTTP, published at mpp.dev. It uses the HTTP 402 status to carry payment terms, and it is a separate specification with its own schemes and its own supported networks.","path":"/glossary/mpp"},{"slug":"coinbase-cdp","title":"Coinbase Developer Platform (CDP)","kind":"player","short":"Coinbase Developer Platform (CDP) is Coinbase's developer product suite. In the x402 ecosystem it operates a facilitator — the service that verifies and settles payments for sellers that configure it — and publishes the discovery catalogue attached to that facilitator, the x402 Bazaar.","path":"/glossary/coinbase-cdp"},{"slug":"x402-foundation","title":"x402 Foundation","kind":"player","short":"The x402 Foundation is the organization that stewards the x402 specification. The protocol's public repository is published under its GitHub organization, which is the source of record for the schemes, the challenge format and the facilitator operations.","path":"/glossary/x402-foundation"},{"slug":"x402-org-facilitator","title":"x402.org facilitator","kind":"player","short":"The x402.org facilitator is the public facilitator served from the protocol's own project site. It verifies and settles payments for sellers that configure it, and it maintains a discovery catalogue of its own, separate from any other facilitator's.","path":"/glossary/x402-org-facilitator"}],"selected":{"slug":"payto","kind":"term","title":"payTo","question":"What is payTo in x402?","short":"payTo is the field in an x402 payment quote that names the address a payment is sent to. It travels inside the HTTP 402 challenge, so it is chosen by whoever controls the endpoint at the moment of the quote, and it can differ between one request and the next.","mechanism":["Each element of an endpoint's [`accepts` array](/glossary/accepts-array) carries the terms of one payment option: the scheme, the network, the asset, the amount and `payTo`, the receiving address. A client that signs an authorization is authorising a transfer to that address, so `payTo` is the field that decides who is paid.","Nothing in the protocol pins the value. An endpoint may rotate it for ordinary reasons — a new treasury address, a change of operator — and an endpoint that has been compromised can rotate it too. Both look identical in a single request. What tells them apart is a dated series of readings taken by somebody who was already watching."],"citations":[{"url":"https://github.com/x402-foundation/x402","publisher":"x402 Foundation","title":"The x402 specification repository","read_on":"2026-08-27"},{"url":"https://docs.x402.org/core-concepts/http-402","publisher":"x402 project documentation","title":"Core concepts: HTTP 402","read_on":"2026-08-27"}],"handoff":{"routes":["/coverage"],"sentence":"probe402 archives the quote it read at each check, so an endpoint's `payTo` and its changes are on the record — open a tracked endpoint from [the endpoint list](/coverage)."},"related":[{"slug":"accepts-array","title":"accepts array","path":"/glossary/accepts-array"},{"slug":"facilitator","title":"facilitator","path":"/glossary/facilitator"},{"slug":"settlement","title":"settlement","path":"/glossary/settlement"}],"terms_used":["accepts-array"],"last_reviewed":"2026-08-27","review_hash":"dfdc65ea64f5eb4f","url":"https://probe402.com/glossary/payto"},"requested_entry_problem":null}