How to Use Multicall3 for Private Transactions

Multicall3 batches multiple operations into a single transaction with atomic execution.

Multicall3 batches multiple operations into a single transaction with atomic execution using bsc_private_tx to get MEV protection with internal fee payment.

This is very good for most use cases, e.g., DEX swaps, token purchases, etc but consumes a lot of gas. If any part fails, the entire transaction reverts.

How it works

This is how Multicall3 works:

Prerequisites

You must have the following:

• Node.js v18 or later installed

• A funded BSC wallet with sufficient BNB for transactions and gas

• GetBlock's BSC Accelerated Dedication Node

Reference Addresses

Address	Purpose
0xcA11bde05977b3631167028862bE2a173976CA11	Multicall3 contract
0x6374Ca2da5646C73Eb444aB99780495d61035f9b	BloXroute fee recipient

Quickstart

1

Set up the project

npm

mkdir multicall3-example
cd multicall3-example
npm init -y
npm install ws ethers dotenv

yarn

2

Create a new file named index.js. This is where you will make your first call.

3

Set the ES module "type": "module" in your package.json.

4

Add the following code to index.js:

The following example demonstrates a simple BNB transfer with a priority fee:

import Websocket from 'ws';
import ethers from 'ethers';

const SIDECAR_URL = 'ws://localhost:28334/ws';
const PRIVATE_KEY = 'your-private-key';
const RPC_URL = 'https://bsc-dataseed.binance.org';

// Constants
const MULTICALL3 = '0xcA11bde05977b3631167028862bE2a173976CA11';
const BLOXROUTE_FEE = '0x6374Ca2da5646C73Eb444aB99780495d61035f9b';

const MULTICALL_ABI = [
  'function aggregate3Value(tuple(address target, bool allowFailure, uint256 value, bytes callData)[] calls) payable returns (tuple(bool success, bytes returnData)[])'
];

async function sendPrivateTxWithTip() {
  const provider = new ethers.JsonRpcProvider(RPC_URL);
  const wallet = new ethers.Wallet(PRIVATE_KEY, provider);
  
  console.log('Wallet:', wallet.address);
  
  // Define amounts
  const tipAmount = ethers.parseEther('0.0001');      // 0.0001 BNB tip
  const transferAmount = ethers.parseEther('0.001');  // Your actual transfer
  const totalValue = tipAmount + transferAmount;
  
  // Build Multicall3 calls
  const calls = [
    {
      target: BLOXROUTE_FEE,      // Tip payment FIRST
      allowFailure: false,
      value: tipAmount,
      callData: '0x'              // Empty = simple transfer
    },
    {
      target: '0xYOUR_RECIPIENT', // Your actual transaction
      allowFailure: false,
      value: transferAmount,
      callData: '0x'              // Or your contract calldata
    }
  ];
  
  // Encode Multicall3 call
  const multicall = new ethers.Contract(MULTICALL3, MULTICALL_ABI, wallet);
  const data = multicall.interface.encodeFunctionData('aggregate3Value', [calls]);
  
  // Get nonce
  const nonce = await provider.getTransactionCount(wallet.address);
  
  // Sign transaction
  const signedTx = await wallet.signTransaction({
    nonce: nonce,
    to: MULTICALL3,
    value: totalValue,
    data: data,
    gasPrice: ethers.parseUnits('3', 'gwei'),
    gasLimit: 150000,  // Higher for Multicall3
    chainId: 56
  });
  
  console.log('Transaction built:');
  console.log('  Tip:', ethers.formatEther(tipAmount), 'BNB');
  console.log('  Transfer:', ethers.formatEther(transferAmount), 'BNB');
  console.log('  Total:', ethers.formatEther(totalValue), 'BNB');
  
  // Send via bsc_private_tx
  const ws = new WebSocket(SIDECAR_URL);
  
  ws.on('open', () => {
    const request = {
      jsonrpc: '2.0',
      id: 1,
      method: 'bsc_private_tx',
      params: {
        transaction: signedTx.slice(2),
        mev_builders: ['all']
      }
    };
    
    console.log('\nSending private TX with tip...');
    ws.send(JSON.stringify(request));
  });
  
  ws.on('message', (data) => {
    const response = JSON.parse(data);
    
    if (response.result) {
      console.log('\n✅ Transaction submitted!');
      console.log('TX Hash:', response.result.txHash);
      console.log('BSCScan:', `https://bscscan.com/tx/${response.result.txHash}`);
    } else {
      console.error('\n❌ Error:', response.error);
    }
    
    ws.close();
  });
}

sendPrivateTxWithTip().catch(console.error);

5

Run the code using this command:

node index.js

6

Sample response

//

Extension sample

You can extend this code for a DEX swap by encoding the router call and including it as the second Multicall3 call:

const PANCAKE_ROUTER = '0x10ED43C718714eb63d5aA57B78B54704E256024E';
const WBNB = '0xbb4CdB9CBd36B01bD1cBaEBF2De08d9173bc095c';
const TOKEN_ADDRESS = '0xYOUR_TOKEN_ADDRESS';

// Build the swap calldata
const routerABI = [
  'function swapExactETHForTokens(uint256 amountOutMin, address[] path, address to, uint256 deadline)'
];
const router = new ethers.Contract(PANCAKE_ROUTER, routerABI, wallet);

const deadline = Math.floor(Date.now() / 1000) + 300;  // 5 minutes from now
const swapData = router.interface.encodeFunctionData('swapExactETHForTokens', [
  minAmountOut,
  [WBNB, TOKEN_ADDRESS],
  wallet.address,
  deadline
]);

// Construct the Multicall3 calls
const calls = [
  {
    target: BLOXROUTE_FEE,
    allowFailure: false,
    value: ethers.parseEther('0.0005'),  // Priority fee
    callData: '0x'
  },
  {
    target: PANCAKE_ROUTER,
    allowFailure: false,
    value: ethers.parseEther('1.0'),  // Swap amount
    callData: swapData
  }
];

Troubleshooting

Problem	Solution
"Multicall3: call failed"	Check you have enough BNB for all calls + gas Increase gas limit to 200000 Verify target addresses are correct
TX not included	Increase tip amount Check if you're rate limited Verify TX is valid (simulate first)
Low priority despite tip	Increase tip amount Check builder status Try different builders: mev_builders: ["48club", "bloxroute"]

Conclusion

This is the simplest method to add tips to private transactions by batching multiple operations into a single transaction with atomic execution. This is very good and highly recommended for day-to-day activities like sending transactions or DEX swaps.