Concepts

What x402 is, in plain English

x402 lets one piece of software pay another for a single request — a fraction of a cent, no subscription, no sign-up form. It is an open standard built on an HTTP status code that sat unused for almost thirty years. This page explains the four steps behind every row in the explorer.

The whole flow, four steps

GET1/4
A program asks for somethingNo account, no API key, no card on file. It just makes the request — the same request a browser would make.
4022/4
The server says: that costs money402 Payment Required is an HTTP status code that has existed since 1997 and was never used for anything. x402 finally gives it a meaning: the server answers with the price, the asset, and the address to pay.
SIG3/4
The caller signs a permission slipNot a transfer — a signature. It says who pays, who gets paid, how much, and until when. No gas is spent and nothing touches the chain yet. The caller retries the same request with that signature attached.
2004/4
A facilitator turns it into a paymentThe facilitator checks the signature, broadcasts it to Arc and pays the gas. USDC moves from payer to payee, the server returns 200, the data comes back. Start to finish: under a second.

Wicket only sees step four. Steps one to three happen over HTTP between two servers and leave no trace on any chain. What lands on Arc is the settlement — and that is what this site indexes.

What the 402 actually looks like

A server that wants to be paid answers like this. The useful part is that the price and the destination travel inside the response, so the caller needs no prior relationship with the seller:

response from the seller

HTTP/1.1 402 Payment Required
Content-Type: application/json

{
  "x402Version": 2,
  "accepts": [{
    "scheme": "exact",
    "network": "eip155:5042",
    "asset": "0x3600000000000000000000000000000000000000",
    "maxAmountRequired": "10000",
    "payTo": "0x6676…3b23",
    "resource": "https://api.example.com/forecast"
  }]
}

The caller signs an authorization for that exact amount and repeats the request with it attached:

the retry

GET /forecast HTTP/1.1
Host: api.example.com
X-PAYMENT: <base64 of the signed authorization>

If the payment verifies, the seller returns 200 and the content. That is the whole protocol: 402 → 200.

Why a facilitator exists at all

The buyer signs, but someone has to put that signature on the chain and pay the gas for it. That someone is the facilitator. It is a normal wallet running a normal service — it verifies the authorization, broadcasts it, and tells the seller whether it went through.

—It never takes custody. The signature moves USDC straight from payer to payee; the facilitator only submits it.
—It pays the gas, which on Arc is itself USDC. That is its cost of doing business.
—It is visible on chain whether it wants to be or not — which is exactly why Wicket can count facilitators nobody has ever named.

Arc changes the calculus

On most chains the buyer cannot broadcast the payment itself, because it would need the native gas token — ETH, SOL, something that is not USDC. On Arc, gas is USDC, so a buyer holding nothing but USDC could settle its own payment. The facilitator becomes a convenience rather than a requirement. Whether the market keeps using facilitators anyway is one of the open questions this explorer exists to answer.

The words you will see on this site

Term	What it means here
Settle	One on-chain transaction that carried out an x402 payment. Every row in the feed is one settle.
Facilitator	The wallet that broadcast the settle and paid the gas. Wicket takes it from `tx.from`.
Payer	The address whose USDC moved. It signed the authorization but never sent a transaction.
Payee	The address that received the USDC. Usually the service being paid for.
Authorization	An EIP-3009 signature: pay this much, to this address, valid between these times, with this one-time nonce. On chain it is `transferWithAuthorization` or `receiveWithAuthorization`.
Value	The amount moved, in the smallest USDC unit. 10,000 means $0.01.
Reverted	The transaction was mined but failed — an expired or already-used authorization, most often. Reverted settles are counted separately and never added to volume.

Read further

—x402.org — the specification, now maintained under the Linux Foundation
—EIP-3009 — the signature standard every settle on this site uses
—Methodology — how Wicket turns those transactions into the numbers you see

The whole flow, four steps

GET1/4

A program asks for somethingNo account, no API key, no card on file. It just makes the request — the same request a browser would make.

4022/4

The server says: that costs money402 Payment Required is an HTTP status code that has existed since 1997 and was never used for anything. x402 finally gives it a meaning: the server answers with the price, the asset, and the address to pay.

SIG3/4

The caller signs a permission slipNot a transfer — a signature. It says who pays, who gets paid, how much, and until when. No gas is spent and nothing touches the chain yet. The caller retries the same request with that signature attached.

2004/4

A facilitator turns it into a paymentThe facilitator checks the signature, broadcasts it to Arc and pays the gas. USDC moves from payer to payee, the server returns 200, the data comes back. Start to finish: under a second.