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How an x402 payment works
An x402 exchange adds payment negotiation to an ordinary request for an HTTP resource, such as an API endpoint. The exact payment method and settlement behavior depend on the scheme, network and implementation.
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- The client requests a resource. It sends an HTTP request to a server hosting an API or another protected digital resource.
- The server describes its payment requirements. If payment is required, the server responds with HTTP 402 and structured requirements. In the current v2 HTTP binding, the canonical location is the base64-encoded
PAYMENT-REQUIREDheader. Requirements may specify acceptable schemes and networks, the amount, asset, payee and timeout information. - The client selects a compatible option. It creates a
PaymentPayloadfor an offered scheme and network it supports. This requires suitable payment or signing capability and, where applicable, access to funds. - The client retries the request. It sends the payment payload in the
PAYMENT-SIGNATUREheader. A client that already knows the resource’s requirements may be able to skip the initial discovery request and 402 response. - The server verifies, executes and settles according to the selected flow. Verification may happen locally or through a facilitator’s read-only
/verifyendpoint when that flow uses one. The server then performs the protected work and settles in the order required by the flow. - The server returns the result. If the request succeeds, the server responds with the resource and a payment response.
HTTP 402 is the signal that payment is required; it does not charge the client. x402 supplies the structured requirements, payload conventions and verification-and-settlement interaction around that status code. A compatible client and server still need to support the chosen payment arrangement.
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When payment happens: three flow models
The x402 v2 specification describes three flow models. They trade off how much payment assurance the server has before doing work against whether funds should move only after successful execution. The available choices depend on the scheme and network; an implementation is not guaranteed to support all three.
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| Flow | Sequence | Practical trade-off |
|---|---|---|
| Authorization | Verify, execute the resource, settle, respond. | Funds move after successful resource execution. |
| Upfront | Settle, execute the resource, respond. | Payment is committed before execution; this flow omits a separate /verify step. |
| Escrow | Commit a deposit or ceiling, execute the resource, then settle again to record the final charge. | Allows a committed amount to cover work whose final charge is determined after execution. |
The specification says clients should skip payment-flow combinations they do not recognize. If both authorization and a pre-execution settlement option are offered, it advises preferring authorization.
What a facilitator does—and whether one is required
A facilitator is a service role, not a single mandatory company. Depending on the supported network and flow, a facilitator can verify payment authorization and submit settlement. A resource server can instead run its own facilitator or self-facilitate.
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For a production deployment, the x402 Foundation repository advises operators to choose a facilitation model deliberately. It cautions against assuming that the public x402.org facilitator is the default production path for mainnet EVM routes. The appropriate model depends on the target network, operational requirements and the trust and reliability the server operator is willing to place in an external service.
What x402 standardizes—and what still varies
The x402 Foundation describes the protocol as open and extensible across transports and networks, rather than dependent on one party. The v2 specification records support patterns for multiple schemes, networks and transports. It also says facilitator APIs are currently standardized as HTTP endpoints, even though the core protocol is transport-agnostic.
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That extensibility is not the same as universal support. Before integrating, confirm that both client and server support the exact scheme, network, asset and transfer mechanism, as well as any relevant timeout constraints. Do not assume a facilitator supports every network or that a client can interpret every payment flow.
The protocol is designed to support pay-per-use access without requiring x402 itself to use accounts, subscriptions or a conventional checkout page. But an implementation may still impose account or other requirements. Likewise, an agent cannot pay merely because an endpoint uses HTTP 402: it needs compatible payment and signing capabilities, an acceptable payment option and the resources to use it.
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Current v2 headers and older examples
The v2 specification’s version history lists v2.0 as dated 2025-12-9. It records changes including CAIP-2 network identifiers, restructured PaymentPayload and PaymentRequired data, separation of ResourceInfo and support for extensions.
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In the current v2 HTTP binding, the header names are PAYMENT-REQUIRED, PAYMENT-SIGNATURE and PAYMENT-RESPONSE. Some older Coinbase explainers and the whitepaper use X-PAYMENT and X-PAYMENT-RESPONSE; treat those as older examples, not the current v2 wire terminology.
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Finding x402-enabled resources
The v2 specification describes discovery APIs for x402-enabled resources and a Bazaar concept for finding monetized APIs and services. Discovery metadata can include a resource identifier, supported protocol version, payment requirements and update time. A directory listing can help a client find a service, but it does not establish the resource’s quality or trustworthiness.
Costs, settlement and adoption claims
The project describes x402 as having zero protocol fees while acknowledging nominal payment-network fees. That does not mean a payment is free: actual costs and confirmation behavior depend on the implementation and network. Claims such as “instant” or “zero fees” need to specify which network and what “settlement” means, as well as who pays network costs.
When observed on 2026-10-04, x402.org’s rolling last-30-days dashboard displayed 75.41 million transactions, $24.24 million in volume, 94.06 thousand buyers and 22 thousand sellers. These are counters published by the project homepage, not independently validated statistics; the panel does not establish what share of activity is truly agent-driven.
Governance and project context
In an announcement dated July 14, 2026, the Linux Foundation said the x402 Foundation had become operational under open governance and that Coinbase had completed its contribution of the protocol. The announcement said 40 organizations had joined, including payments firms, cloud providers, networks and technology companies. Membership indicates participation in the ecosystem, not necessarily product integration or endorsement.
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