Build USDC transfer authorization

Build the EIP-3009 transferWithAuthorization typed data for a gasless USDC transfer on Base/Polygon/Arbitrum/Optimism/Ethereum — the exact EIP-712 object an agent signs with its OWN key to authorize an x402 payment. We construct it; we never sign or send. Non-custodial.

Input

Field	Type	Description
from *	string	payer address (the wallet that will sign)
to *	string	recipient address
amount *	number	USDC amount (e.g. 0.01)
network	string	chain: base | polygon | arbitrum | optimism | ethereum (default base)
validForSeconds	number	how long the authorization is valid (default 3600)

Example output

{
  "typedData": {
    "domain": {
      "name": "USD Coin",
      "version": "2",
      "chainId": 8453,
      "verifyingContract": "0x833589f…"
    },
    "primaryType": "TransferWithAuthorization",
    "message": {}
  },
  "network": "base"
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/transfer-authorization \
  -H "Content-Type: application/json" \
  -d '{"from":"0x1111111111111111111111111111111111111111","to":"0x2222222222222222222222222222222222222222","amount":0.01,"network":"base"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/transfer-authorization", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "from": "0x1111111111111111111111111111111111111111",
    "to": "0x2222222222222222222222222222222222222222",
    "amount": 0.01,
    "network": "base"
  }),
});

Wallet-only. This tool reaches the network/browser/storage, so it is paid in USDC via x402 (no proof-of-work tier).

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