Send batch USDC transfers

Use the Multicall3From contract to batch multiple USDC transfers into one Arc transaction. This tutorial shows the full flow with viem, ethers.js, Python, and curl. You will configure a client, encode two ERC-20 transfer(...) subcalls, submit them through Multicall3From.aggregate3(...), and verify the resulting Transfer events. To learn how Multicall3From preserves your wallet as the sender, see Batched transactions.

Prerequisites

Before you begin, ensure that you’ve:

Installed Node.js v22+ for the TypeScript examples, or Python 3.10+ for the Python example.
Created an Arc Testnet wallet.
Funded the wallet with testnet USDC from the Circle Faucet.
Chosen two recipient addresses on Arc Testnet.

Step 1. Set up the project

Create a new project and install the dependencies for the client library you want to use:

mkdir arc-batched-transfers
cd arc-batched-transfers
npm init -y
npm pkg set type=module
npm install dotenv ethers tsx typescript viem

mkdir arc-batched-transfers
cd arc-batched-transfers
python3 -m venv .venv
source .venv/bin/activate
pip install web3 python-dotenv

Create an .env file:

Shell

touch .env

Add your configuration:

.env

PRIVATE_KEY=YOUR_PRIVATE_KEY
RECIPIENT_ONE_ADDRESS=RECIPIENT_ONE_ADDRESS
RECIPIENT_TWO_ADDRESS=RECIPIENT_TWO_ADDRESS
RPC_URL=https://rpc.testnet.arc.io

Replace YOUR_PRIVATE_KEY with the 0x-prefixed private key for the funded wallet. Replace each recipient value with an Arc Testnet address.

Step 2. Review the contract address and ABI

Arc Testnet uses the following predeployed contracts for this tutorial:

Contract	Address
`Multicall3From`	`0x522fAf9A91c41c443c66765030741e4AaCe147D0`
`USDC`	`0x3600000000000000000000000000000000000000`

For the full address list, see contract addresses. Create multicall3from-abi.json in your project:

multicall3from-abi.json

[
  {
    "type": "function",
    "name": "aggregate3",
    "stateMutability": "nonpayable",
    "inputs": [
      {
        "name": "calls",
        "type": "tuple[]",
        "components": [
          { "name": "target", "type": "address" },
          { "name": "allowFailure", "type": "bool" },
          { "name": "callData", "type": "bytes" }
        ]
      }
    ],
    "outputs": [
      {
        "name": "returnData",
        "type": "tuple[]",
        "components": [
          { "name": "success", "type": "bool" },
          { "name": "returnData", "type": "bytes" }
        ]
      }
    ]
  }
]

The script you build in the next steps loads this ABI file from the project root.

Step 3. Configure the client connection

Create the script file for your client library. The first chunk reads the wallet and recipient configuration from .env, sets the contract addresses, loads the Multicall3From ABI, and creates the clients that read chain state and submit transactions.

Viem
ethers.js
Python

Create viem-batch.ts:

TypeScript

import "dotenv/config";
import { readFileSync } from "node:fs";
import {
  type Address,
  createPublicClient,
  createWalletClient,
  defineChain,
  encodeFunctionData,
  erc20Abi,
  getAddress,
  http,
  parseEventLogs,
  parseUnits,
} from "viem";
import { privateKeyToAccount } from "viem/accounts";

const rpcUrl = process.env.RPC_URL ?? "https://rpc.testnet.arc.io";
const privateKey = process.env.PRIVATE_KEY as `0x${string}`;
const recipients = [
  getAddress(process.env.RECIPIENT_ONE_ADDRESS as Address),
  getAddress(process.env.RECIPIENT_TWO_ADDRESS as Address),
];

const arcTestnet = defineChain({
  id: 5042002,
  name: "Arc Testnet",
  nativeCurrency: { name: "USDC", symbol: "USDC", decimals: 18 },
  rpcUrls: { default: { http: [rpcUrl] } },
  blockExplorers: {
    default: { name: "ArcScan", url: "https://testnet.arcscan.app" },
  },
  testnet: true,
});

const multicall3FromAddress = "0x522fAf9A91c41c443c66765030741e4AaCe147D0";
const usdcAddress = "0x3600000000000000000000000000000000000000";
const multicall3FromAbi = JSON.parse(
  readFileSync("multicall3from-abi.json", "utf8"),
);

const account = privateKeyToAccount(privateKey);
const publicClient = createPublicClient({
  chain: arcTestnet,
  transport: http(rpcUrl),
});
const walletClient = createWalletClient({
  account,
  chain: arcTestnet,
  transport: http(rpcUrl),
});

Create ethers-batch.ts:

TypeScript

import "dotenv/config";
import { readFileSync } from "node:fs";
import { ethers } from "ethers";

const rpcUrl = process.env.RPC_URL ?? "https://rpc.testnet.arc.io";
const privateKey = process.env.PRIVATE_KEY as string;
const recipients = [
  ethers.getAddress(process.env.RECIPIENT_ONE_ADDRESS as string),
  ethers.getAddress(process.env.RECIPIENT_TWO_ADDRESS as string),
];

const multicall3FromAddress = "0x522fAf9A91c41c443c66765030741e4AaCe147D0";
const usdcAddress = "0x3600000000000000000000000000000000000000";
const explorerUrl = "https://testnet.arcscan.app";

const multicall3FromAbi = JSON.parse(
  readFileSync("multicall3from-abi.json", "utf8"),
);
const erc20Abi = [
  "function transfer(address to, uint256 amount) returns (bool)",
  "event Transfer(address indexed from, address indexed to, uint256 value)",
];

const provider = new ethers.JsonRpcProvider(rpcUrl, {
  chainId: 5042002,
  name: "arc-testnet",
});
const wallet = new ethers.Wallet(privateKey, provider);
const multicall3FromInterface = new ethers.Interface(multicall3FromAbi);
const erc20Interface = new ethers.Interface(erc20Abi);

Create python-batch.py:

Python

import json
import os

from dotenv import load_dotenv
from web3 import Web3
from web3.logs import DISCARD

load_dotenv()

rpc_url = os.getenv("RPC_URL", "https://rpc.testnet.arc.io")
private_key = os.environ["PRIVATE_KEY"]
recipients = [
    Web3.to_checksum_address(os.environ["RECIPIENT_ONE_ADDRESS"]),
    Web3.to_checksum_address(os.environ["RECIPIENT_TWO_ADDRESS"]),
]

multicall3_from_address = Web3.to_checksum_address(
    "0x522fAf9A91c41c443c66765030741e4AaCe147D0"
)
usdc_address = Web3.to_checksum_address("0x3600000000000000000000000000000000000000")
explorer_url = "https://testnet.arcscan.app"

with open("multicall3from-abi.json", encoding="utf-8") as abi_file:
    multicall3_from_abi = json.load(abi_file)
erc20_abi = [
    {
        "type": "function",
        "name": "transfer",
        "stateMutability": "nonpayable",
        "inputs": [
            {"name": "to", "type": "address"},
            {"name": "amount", "type": "uint256"},
        ],
        "outputs": [{"name": "", "type": "bool"}],
    },
    {
        "type": "event",
        "name": "Transfer",
        "anonymous": False,
        "inputs": [
            {"name": "from", "type": "address", "indexed": True},
            {"name": "to", "type": "address", "indexed": True},
            {"name": "value", "type": "uint256", "indexed": False},
        ],
    },
]

w3 = Web3(Web3.HTTPProvider(rpc_url))
account = w3.eth.account.from_key(private_key)
multicall3_from = w3.eth.contract(
    address=multicall3_from_address,
    abi=multicall3_from_abi,
)
usdc = w3.eth.contract(address=usdc_address, abi=erc20_abi)

The public clients read chain state, the wallet or account objects sign transactions, and the contract interfaces encode the Multicall3From and ERC-20 calls.

Step 4. Encode the transfer calls

Add a chunk that sets the USDC amount and builds one ERC-20 transfer(...) subcall for each recipient. Each subcall targets the USDC contract, sets allowFailure to false, and includes the encoded transfer calldata.

Viem
ethers.js
Python

TypeScript

const amount = parseUnits("1", 6);

const calls = recipients.map((recipient) => ({
  target: usdcAddress,
  allowFailure: false,
  callData: encodeFunctionData({
    abi: erc20Abi,
    functionName: "transfer",
    args: [recipient, amount],
  }),
}));

TypeScript

const amount = ethers.parseUnits("1", 6);

const calls = recipients.map((recipient) => ({
  target: usdcAddress,
  allowFailure: false,
  callData: erc20Interface.encodeFunctionData("transfer", [recipient, amount]),
}));
const aggregateData = multicall3FromInterface.encodeFunctionData("aggregate3", [
  calls,
]);

Python

amount = 1_000_000

calls = []
for recipient in recipients:
    transfer_data = usdc.functions.transfer(
        recipient,
        amount,
    )._encode_transaction_data()
    calls.append(
        (
            usdc_address,
            False,
            bytes.fromhex(transfer_data[2:]),
        )
    )

1000000 is 1 USDC in base units because the USDC ERC-20 interface uses 6 decimals.

Step 5. Confirm `Multicall3From` is deployed

Before sending a transaction, check that the configured Multicall3From address has deployed bytecode.

Viem
ethers.js
Python

TypeScript

const multicall3FromCode = await publicClient.getCode({
  address: multicall3FromAddress,
});
if (!multicall3FromCode || multicall3FromCode === "0x") {
  throw new Error(`Multicall3From is not deployed at ${multicall3FromAddress}`);
}

TypeScript

const multicall3FromCode = await provider.getCode(multicall3FromAddress);
if (multicall3FromCode === "0x") {
  throw new Error(`Multicall3From is not deployed at ${multicall3FromAddress}`);
}

Python

multicall3_from_code = w3.eth.get_code(multicall3_from_address)
if multicall3_from_code == b"":
    raise RuntimeError(
        f"Multicall3From is not deployed at {multicall3_from_address}"
    )

If the bytecode check returns empty code, confirm that your RPC_URL points to Arc Testnet and that the address matches the table in Step 2.

Step 6. Simulate and send the batch

Simulate the aggregate3(...) call before sending the transaction. The simulation confirms that each encoded subcall can succeed from your wallet.

Viem
ethers.js
Python

TypeScript

const simulation = await publicClient.simulateContract({
  account,
  address: multicall3FromAddress,
  abi: multicall3FromAbi,
  functionName: "aggregate3",
  args: [calls],
});

const simulatedResults = simulation.result as {
  success: boolean;
  returnData: `0x${string}`;
}[];
if (!simulatedResults.every((result) => result.success)) {
  throw new Error(
    `Expected all simulated subcalls to succeed: ${JSON.stringify(
      simulatedResults,
    )}`,
  );
}

const hash = await walletClient.writeContract(simulation.request);
const receipt = await publicClient.waitForTransactionReceipt({ hash });
if (receipt.status !== "success") {
  throw new Error(`Batched transaction reverted: ${hash}`);
}

TypeScript

const [simulatedResults] = multicall3FromInterface.decodeFunctionResult(
  "aggregate3",
  await provider.call({
    from: wallet.address,
    to: multicall3FromAddress,
    data: aggregateData,
  }),
) as unknown as [{ success: boolean; returnData: string }[]];
if (!simulatedResults.every((result) => result.success)) {
  throw new Error(
    `Expected all simulated subcalls to succeed: ${JSON.stringify(
      simulatedResults,
    )}`,
  );
}

const tx = await wallet.sendTransaction({
  to: multicall3FromAddress,
  data: aggregateData,
});
const receipt = await tx.wait();
if (!receipt) {
  throw new Error("Transaction was not mined");
}
if (receipt.status !== 1) {
  throw new Error(`Batched transaction reverted: ${tx.hash}`);
}

Python

simulated_results = multicall3_from.functions.aggregate3(calls).call(
    {"from": account.address}
)
if not all(result[0] for result in simulated_results):
    raise RuntimeError(f"Expected all simulated subcalls to succeed: {simulated_results}")

latest_block = w3.eth.get_block("latest")
priority_fee = w3.to_wei(1, "gwei")
base_fee = latest_block["baseFeePerGas"]

transaction = multicall3_from.functions.aggregate3(calls).build_transaction(
    {
        "from": account.address,
        "nonce": w3.eth.get_transaction_count(account.address),
        "chainId": w3.eth.chain_id,
        "maxPriorityFeePerGas": priority_fee,
        "maxFeePerGas": (base_fee * 2) + priority_fee,
    }
)

signed = account.sign_transaction(transaction)
tx_hash = w3.eth.send_raw_transaction(signed.raw_transaction)
receipt = w3.eth.wait_for_transaction_receipt(tx_hash)
if receipt["status"] != 1:
    raise RuntimeError(f"Batched transaction reverted: {Web3.to_hex(tx_hash)}")

The receipt is reused in the next step to check the emitted USDC Transfer events.

Step 7. Verify the transfer events

Decode the USDC logs from the receipt and confirm that each expected transfer is present.

Viem
ethers.js
Python

TypeScript

const transferLogs = parseEventLogs({
  abi: erc20Abi,
  eventName: "Transfer",
  logs: receipt.logs.filter(
    (log) => log.address.toLowerCase() === usdcAddress.toLowerCase(),
  ),
});

for (const recipient of recipients) {
  const transfer = transferLogs.find(
    (log) =>
      getAddress(log.args.from) === account.address &&
      getAddress(log.args.to) === recipient &&
      log.args.value === amount,
  );

  if (!transfer) {
    throw new Error(`Missing expected USDC Transfer log to ${recipient}`);
  }
}

console.log(
  "Transaction:",
  `${arcTestnet.blockExplorers.default.url}/tx/${hash}`,
);
console.log("Block:", receipt.blockNumber.toString());
console.log("Sender:", account.address);
console.log(
  "Transfers:",
  recipients.map((recipient) => ({
    to: recipient,
    amount: amount.toString(),
  })),
);

TypeScript

const transferEvents: ethers.LogDescription[] = [];
for (const log of receipt.logs) {
  if (log.address.toLowerCase() !== usdcAddress.toLowerCase()) continue;

  const parsed = erc20Interface.parseLog(log);
  if (parsed?.name === "Transfer") transferEvents.push(parsed);
}

for (const recipient of recipients) {
  const transfer = transferEvents.find(
    (event) =>
      event.args.from.toLowerCase() === wallet.address.toLowerCase() &&
      event.args.to.toLowerCase() === recipient.toLowerCase() &&
      event.args.value === amount,
  );

  if (!transfer) {
    throw new Error(`Missing expected USDC Transfer log to ${recipient}`);
  }
}

console.log("Transaction:", `${explorerUrl}/tx/${tx.hash}`);
console.log("Block:", receipt.blockNumber);
console.log("Sender:", wallet.address);
console.log(
  "Transfers:",
  recipients.map((recipient) => ({
    to: recipient,
    amount: amount.toString(),
  })),
);

Python

transfer_events = usdc.events.Transfer().process_receipt(receipt, errors=DISCARD)
for recipient in recipients:
    transfer = next(
        (
            event
            for event in transfer_events
            if Web3.to_checksum_address(event["args"]["from"]) == account.address
            and Web3.to_checksum_address(event["args"]["to"]) == recipient
            and event["args"]["value"] == amount
        ),
        None,
    )
    if transfer is None:
        raise RuntimeError(f"Missing expected USDC Transfer log to {recipient}")

print("Transaction:", f"{explorer_url}/tx/{Web3.to_hex(tx_hash)}")
print("Block:", receipt["blockNumber"])
print("Sender:", account.address)
print(
    "Transfers:",
    [{"to": recipient, "amount": str(amount)} for recipient in recipients],
)

The from value in each expected Transfer event is your wallet address. That check confirms that the target USDC contract saw your wallet as the sender for each subcall.

Step 8. Run the script

Run the command for the script you created:

npx tsx --env-file=.env viem-batch.ts

npx tsx --env-file=.env ethers-batch.ts

python python-batch.py

Successful output includes the transaction URL, block number, sender, and both recipient transfers:

Transaction: https://testnet.arcscan.app/tx/0x...
Block: 123456
Sender: 0xYourWallet...
Transfers: [
  { to: "0xRecipientOne...", amount: "1000000" },
  { to: "0xRecipientTwo...", amount: "1000000" }
]

Step 9. Check JSON-RPC directly with curl

Use curl for read-only JSON-RPC checks, such as verifying deployed bytecode or reading a transaction receipt. Use a client library such as viem, ethers.js, or web3.py to sign and submit the transaction itself.

MULTICALL3FROM_ADDRESS=0x522fAf9A91c41c443c66765030741e4AaCe147D0
RPC_URL=https://rpc.testnet.arc.io

curl --request POST "$RPC_URL" \
  --header "content-type: application/json" \
  --data '{
    "jsonrpc": "2.0",
    "method": "eth_getCode",
    "params": ["'"$MULTICALL3FROM_ADDRESS"'", "latest"],
    "id": 1
  }'

TRANSACTION_HASH=0xYOUR_TRANSACTION_HASH
RPC_URL=https://rpc.testnet.arc.io

curl --request POST "$RPC_URL" \
  --header "content-type: application/json" \
  --data '{
    "jsonrpc": "2.0",
    "method": "eth_getTransactionReceipt",
    "params": ["'"$TRANSACTION_HASH"'"],
    "id": 1
  }'

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Send batch USDC transfers

Prerequisites

Step 1. Set up the project

Step 2. Review the contract address and ABI

Step 3. Configure the client connection

Step 4. Encode the transfer calls

Step 5. Confirm `Multicall3From` is deployed

Step 6. Simulate and send the batch

Step 7. Verify the transfer events

Step 8. Run the script

Step 9. Check JSON-RPC directly with curl

​Prerequisites

​Step 1. Set up the project

​Step 2. Review the contract address and ABI

​Step 3. Configure the client connection

​Step 4. Encode the transfer calls

​Step 5. Confirm Multicall3From is deployed

​Step 6. Simulate and send the batch

​Step 7. Verify the transfer events

​Step 8. Run the script

​Step 9. Check JSON-RPC directly with curl

Prerequisites

Step 1. Set up the project

Step 2. Review the contract address and ABI

Step 3. Configure the client connection

Step 4. Encode the transfer calls

Step 5. Confirm `Multicall3From` is deployed

Step 6. Simulate and send the batch

Step 7. Verify the transfer events

Step 8. Run the script

Step 9. Check JSON-RPC directly with curl