x402 facilitator

Arclight runs an open x402 v2 facilitator on Arc. A seller returns HTTP 402 with payment requirements, the buyer signs a USDC or EURC authorization (EIP-3009), and the facilitator verifies it and settles it on chain. Both assets have 6 decimals, so amounts are in 6-decimal units either way.

URL

x402.arclight.finance

NETWORK

eip155:5042

SCHEME

exact

ASSETS

USDC, EURC

Endpoints

GET/supportedWhat we settle: exact, eip155:5042, the asset list, and the signer address.

POST/verifyChecks a signed authorization without touching the chain state. Free, read-only.

POST/settleBroadcasts the transfer from our wallet, waits for the receipt, returns the transaction hash.

GET/healthSigner address, USDC balance (Arc pays gas in USDC), gas budget left for the day, queue depth.

GET/tiersThe ARCLIGHT staking ladder, and how much of today’s sponsored-settle allowance a seller has left.

Payment requirements for Arc

This is what your server puts in the 402 response. The extra block is the EIP-712 domain of the asset you are charging in, and it must match that asset.

{
  "scheme": "exact",
  "network": "eip155:5042",
  "asset": "0x3600000000000000000000000000000000000000",
  "amount": "10000",
  "payTo": "0xYourReceivingAddress",
  "maxTimeoutSeconds": 60,
  "extra": { "name": "USDC", "version": "2" }
}

To charge in euros instead, change those two fields:

"asset": "0xbef5f6d51cb62b58e6a8f77868681825c6fe21c1",
"extra": { "name": "EURC", "version": "2" }

Seller in two lines

Any x402 v2 server SDK works. Set the facilitator URL and the network; the SDK builds the requirements and calls verify and settle for you.

import { HTTPFacilitatorClient } from '@x402/core/server'
import { ExactEvmScheme } from '@x402/evm/exact/server'
import { paymentMiddlewareFromConfig } from '@x402/hono'

const facilitator = new HTTPFacilitatorClient({ url: 'https://x402.arclight.finance' })

app.use('/api/answer', paymentMiddlewareFromConfig(
  {
    'GET /api/answer': {
      accepts: {
        scheme: 'exact',
        network: 'eip155:5042',
        payTo: '0xYourReceivingAddress',
        price: { amount: '10000', asset: '0x3600000000000000000000000000000000000000' },
        maxTimeoutSeconds: 60,
        extra: { name: 'USDC', version: '2' },
      },
      description: 'One answer',
      mimeType: 'application/json',
    },
  },
  facilitator,
  [{ network: 'eip155:5042', server: new ExactEvmScheme() }],
))

Buyer: an agent paying for a call

An EVM key holding USDC, or EURC, on Arc (chain id 5042, RPC https://rpc.mainnet.arc.io).
A seller whose 402 lists network eip155:5042. The Arclight API demo is priced at 0.001 USDC per call.
Nothing from us. The facilitator has no keys, no signup and no allowlist.

import { wrapFetchWithPayment, x402Client } from '@x402/fetch'
import { ExactEvmScheme } from '@x402/evm/exact/client'
import { privateKeyToAccount } from 'viem/accounts'

const signer = privateKeyToAccount(process.env.AGENT_KEY as `0x${string}`)
const client = new x402Client().register('eip155:*', new ExactEvmScheme(signer))
const fetchWithPayment = wrapFetchWithPayment(fetch, client)
const res = await fetchWithPayment('https://api.arclight.finance/v1/x402/demo')

Buyer: a NEAR account, with no Arc key

NEAR's MPC network controls one root key and signs for a derived key only when the call comes from the NEAR account that derives it. The facilitator sees an ordinary secp256k1 signature.

Limits

Verify: 10 a second per IP.
Settle: 2 a second per IP, 60 a minute per receiving address, 20 a minute per payer.
Body: 32 KB.
One settle at a time per authorization.

What the facilitator never does

Hold your funds. The transfer goes from the payer to the seller in one call; our wallet only pays the gas.
Retry a reverted settle.
Ask for a key or a deposit.
Charge a fee. Gas is paid by Arclight inside a daily budget.

Status: x402.arclight.finance/health. Live demo: /x402.