Flashbots Tutorial: Complete Guide to Private MEV Bundles

What is Flashbots?

Flashbots is a research and development organization working on mitigating the negative externalities of MEV extraction. They provide infrastructure that allows users to submit private transaction bundles directly to miners/validators, bypassing the public mempool.

This approach offers several advantages:

• Reduced front-running risk
• Lower gas costs through direct communication
• Ability to execute complex multi-transaction strategies
• Better privacy for trading strategies
• Atomic execution (all transactions succeed or fail together)

Step-by-Step Guide

Bundle Structure

A Flashbots bundle consists of:

• Transactions: Array of transactions to execute atomically
• Block Number: Target block for inclusion
• Min Timestamp: Minimum block timestamp (optional)
• Max Timestamp: Maximum block timestamp (optional)

Example Bundle

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_sendBundle",
  "params": [{
    "txs": [
      "0x02f8...", // Transaction 1
      "0x02f8..."  // Transaction 2
    ],
    "blockNumber": "0x1234567",
    "minTimestamp": null,
    "maxTimestamp": null
  }]
}

Gas Price Optimization

Flashbots uses a first-price auction model. Key considerations:

• Higher gas prices increase inclusion probability
• But reduce profitability due to higher costs
• Monitor historical inclusion rates at different gas levels
• Use tools like our Gas Calculator to optimize
• Consider network congestion when setting prices

Code Examples

JavaScript/TypeScript Example

import { ethers } from 'ethers';

const flashbotsRpc = 'https://rpc.flashbots.net';
const provider = new ethers.JsonRpcProvider(flashbotsRpc);

async function submitBundle(txs: string[], targetBlock: number) {
  const bundle = {
    jsonrpc: '2.0',
    id: 1,
    method: 'eth_sendBundle',
    params: [{
      txs: txs,
      blockNumber: '0x' + targetBlock.toString(16),
    }],
  };
  
  const response = await fetch(flashbotsRpc, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(bundle),
  });
  
  return await response.json();
}

Python Example

import requests
import json

def submit_bundle(txs, target_block):
    url = 'https://rpc.flashbots.net'
    payload = {
        'jsonrpc': '2.0',
        'id': 1,
        'method': 'eth_sendBundle',
        'params': [{
            'txs': txs,
            'blockNumber': hex(target_block),
        }],
    }
    
    response = requests.post(url, json=payload)
    return response.json()

Best Practices

• Start Small: Test with small amounts before scaling up
• Monitor Status: Use Flashbots dashboard to track bundle status
• Optimize Gas: Continuously refine gas prices based on inclusion rates
• Error Handling: Implement robust error handling for failed submissions
• Rate Limiting: Respect rate limits to avoid being blocked
• Simulation: Use Flashbots simulation endpoint to test bundles before submission

Flashbots vs Public Mempool

Learn more in our Flashbots vs Public Mempool comparison.

Additional Resources

• Flashbots Documentation
• Flashbots Protect - Easy bundle submission
• MEV Strategies Guide - Advanced strategies
• Ethereum MEV Guide - Network-specific tips
• Gas Calculator - Optimize gas prices

Next Steps

Ready to start using Flashbots? Here's what to do next:

1. Review the official Flashbots documentation
2. Set up your development environment
3. Test bundle submission in simulation mode
4. Start with small test bundles
5. Monitor and optimize your strategies
6. Consider using FRB Agent for automated MEV trading