Flashbots Bundler

WHAT IT DOES

Flashbots Bundler gives DeFi traders, MEV searchers, and protocol users a powerful tool to build and submit Flashbots bundles for private transaction ordering. It reads live data including mempool state, transaction simulation data, Flashbots relay status, bundle submission history, block state, and gas price oracles. You can bundle multiple transactions together, specify exact ordering, target specific blocks, and submit directly to Flashbots relays to avoid public mempool exposure. The tool shows you in real time the bundle composition, target block, gas price, relay status, and submission results—so you can protect your transactions from front-running and MEV extraction.

HOW TO USE

Connect your EVM wallet. Enter transactions one per line in the format: to,data,value (e.g., 0x...,0x...,0.1). Optionally set a target block number (0 for the next block) and a gas price in Gwei (leave blank for auto). Click "Simulate bundle" to validate transactions and see gas estimates. Use "Check relay status" to verify Flashbots availability on your current chain. Click "Submit bundle" to prepare the bundle for submission. Review the transaction count, target block, gas price, bundle hash, and relay status. Click "Sign & submit" to send the bundle to your wallet for signing and relay submission. After confirmation, the tool displays the bundle submission result and explorer link.

TECHNICAL APPROACH

This tool uses ethers v5.7.2 to build and simulate transaction bundles. It parses user-provided transactions into structured objects with to, data, and value fields. It simulates each transaction using estimateGas() to validate gas requirements and detect reverts. The tool generates a unique bundle hash for tracking and communicates with Flashbots relays (where available) to submit bundles privately, bypassing the public mempool. Bundle ordering is preserved exactly as entered, with transactions executed sequentially in the target block. The tool checks Flashbots relay status by verifying chain support and current block state. All RPC calls are wrapped in a robust error handler that extracts the actual failure reason from Ethers error objects, digging three levels deep to avoid showing "[object Object]" when a call fails.

WHAT IT CANNOT SEE

This tool cannot guarantee bundle inclusion in a specific block. It cannot prevent MEV through other private mempools or non-Flashbots relays. It cannot detect whether a bundle was included in the target block after submission. It cannot simulate the exact state of the target block at the time of inclusion. It cannot account for changes in mempool state between simulation and submission. It cannot guarantee that the relay will accept the bundle or that miners will include it. The tool provides bundle construction and submission capabilities, but it does not guarantee that bundles will be included as intended.

PLEASE NOTE

This tool supports EVM‑compatible chains only (Ethereum, Goerli, Sepolia, Arbitrum, Optimism, Polygon). Flashbots is primarily available on Ethereum Mainnet, Goerli, and Sepolia. Solana, Tron, Starknet, SUI, TON, Aptos, Bitcoin, Cosmos, and XRP are not supported. This is a read‑write tool that requires signing transactions—always verify the bundle contents and ordering before approving. No contract addresses are hardcoded; you enter the transactions you want to bundle. The tool is free and open under the BotGentz PLAYBOOK‑C specification.