Mainnet x402 Facilitator

First x402 facilitator on Ethereum mainnet to use preconfirmations for sub-second USDC settlement.

The Problem

AI agents need to pay for APIs, compute, and data in real-time. Traditional Ethereum payments are too slow (12+ seconds for finality). Existing x402 facilitators only work on Base and Solana, leaving agents unable to access Ethereum's $100B+ in stablecoins and DeFi liquidity.

The Solution

Feature	Value
Sub-second settlement	~1.2s end-to-end via FastRPC preconfirmations (vs 12+ seconds)
Zero gas for agents	Agents only need USDC — no ETH required, gas fully sponsored
Mainnet liquidity	Access Ethereum's largest stablecoin issuance
x402 compatible	Drop-in replacement for Base/Solana facilitators
EIP-3009	Gasless transferWithAuthorization signatures

Live API

https://facilitator.primev.xyz

Endpoint	Description
POST /settle	Verify + settle payment via FastRPC preconfirmation
POST /verify	Validate signature, balance, nonce (dry run)
GET /supported	Return supported schemes and networks

How It Works

Agent                     Resource Server              Facilitator              FastRPC
  │                             │                           │                      │
  │── GET /resource ───────────>│                           │                      │
  │<── 402 + PaymentRequired ───│                           │                      │
  │                             │                           │                      │
  │ (signs transferWithAuthorization - no gas, no ETH)      │                      │
  │                             │                           │                      │
  │── GET /resource ───────────>│                           │                      │
  │   + PAYMENT-SIGNATURE       │── POST /settle ──────────>│── preconfirm ───────>│
  │                             │<── { success, txHash } ───│<── ~100-200ms ───────│
  │<── 200 + response ──────────│                           │                      │

1. Agent requests paid resource → receives 402 with payment requirements
2. Agent signs EIP-3009 transferWithAuthorization (just a signature, no tx, no gas)
3. Agent retries with signature → server calls /settle
4. Facilitator submits to FastRPC → preconfirmed in ~100-200ms
5. Agent receives response immediately

Proof of Work

Confirmed mainnet transactions:

• 0x25919e... — 1 USDC
• 0x1e3fd5... — 1 USDC
• 0x4e8bf1... — 1 USDC (1.2s end-to-end)

Agent Integration

With x402 Libraries (Recommended)

import { withX402 } from "@x402/axios";

const client = withX402(axios, { walletClient });
const response = await client.get("https://api.example.com/paid-endpoint");
// Payment signed and settled automatically on 402 response

Direct API Usage

import { createWalletClient, http } from 'viem'
import { privateKeyToAccount } from 'viem/accounts'
import { mainnet } from 'viem/chains'
import { randomBytes } from 'crypto'

const USDC = '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48'
const FACILITATOR = 'https://facilitator.primev.xyz'

// Sign EIP-3009 authorization
const signature = await walletClient.signTypedData({
  domain: { name: 'USD Coin', version: '2', chainId: 1, verifyingContract: USDC },
  types: {
    TransferWithAuthorization: [
      { name: 'from', type: 'address' },
      { name: 'to', type: 'address' },
      { name: 'value', type: 'uint256' },
      { name: 'validAfter', type: 'uint256' },
      { name: 'validBefore', type: 'uint256' },
      { name: 'nonce', type: 'bytes32' },
    ],
  },
  primaryType: 'TransferWithAuthorization',
  message: {
    from: account.address,
    to: merchantAddress,
    value: BigInt(amount),
    validAfter: 0n,
    validBefore: BigInt(Math.floor(Date.now() / 1000) + 900),
    nonce: `0x${randomBytes(32).toString('hex')}`,
  },
})

// Settle payment
const result = await fetch(`${FACILITATOR}/settle`, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ paymentPayload, paymentRequirements }),
}).then(r => r.json())

// { success: true, transaction: "0x...", network: "eip155:1" }

Server Integration

import { paymentMiddleware } from "@x402/express";

app.use(paymentMiddleware({
  "GET /api/data": {
    accepts: [{
      scheme: "exact",
      network: "eip155:1",
      amount: "1000000", // 1 USDC
      asset: "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
      payTo: "0xYourAddress",
      maxTimeoutSeconds: 60,
    }],
  },
}, { facilitatorUrl: "https://facilitator.primev.xyz" }));

Error Codes

Code	Description
invalid_signature	EIP-712 signature verification failed
insufficient_funds	Payer doesn't have enough USDC
nonce_already_used	Replay protection triggered
authorization_expired	Current time is after validBefore
recipient_mismatch	to doesn't match payTo
insufficient_payment	value is less than required amount

Development

# Run tests
cd contracts && forge test -vvv

# Local dev
cd api && vercel dev

# Deploy
cd api && vercel --prod

Environment Variables

Variable	Description
RELAY_PRIVATE_KEY	Hot wallet for settlement txs
RPC_URL	Ethereum mainnet RPC

Architecture

api/
├── index.ts      # Hono routes
├── settle.ts     # FastRPC submission
├── verify.ts     # EIP-712 signature verification
├── config.ts     # USDC address, FastRPC URL
├── types.ts      # x402 protocol types
└── abi.ts        # USDC ABI

Registry & Ecosystem Listings

Registry	Status	Link
ERC-8004 Identity	Registered — Agent #23175	Etherscan NFT
x402 Ecosystem (coinbase/x402)	PR open	PR #1114
x402scan Explorer (Merit-Systems)	PR open	PR #624
awesome-x402 (xpaysh)	PR open	PR #11
awesome-x402 (Merit-Systems)	PR open	PR #29
awesome-erc8004	PR open	PR #3
x402.watch Directory	Pending — Ethereum mainnet not yet supported	x402.watch
x402 Bazaar	Live	/supported + /discovery/resources

Note: x402.watch currently only lists facilitators on Base, Polygon, and Solana. Ethereum mainnet support has been requested — once added, this facilitator will be listed as "Primev – Ethereum Mainnet with Preconfs" at https://facilitator.primev.xyz.

Links

• x402 Protocol
• Primev FastRPC
• EIP-3009
• mev-commit
• x402.watch Facilitator Directory
• 8004agents.ai Explorer