Backrun Opportunity Executor

WHAT IT DOES

The Backrun Opportunity Executor enables users to execute transactions immediately after a target transaction in the mempool. It reads mempool transaction state, pending transaction data, target transaction hash, calldata, from address, to address, value, and gas price. The tool processes backrun transaction parameters, arbitrage opportunity state, DEX state, token balances, and slippage parameters. It supports backrunTransaction for direct execution, submitBackrunBundle for bundled submission via Flashbots, and executeWithMevGeth for mev-geth compatible execution. The tool reads gas price, base fee, block timestamp, chain ID, transaction nonce, and approval state before execution.

HOW TO USE

Connect your wallet and select the target network. Enter the target transaction hash you wish to backrun, along with the target contract address and target calldata. Provide the backrun transaction calldata that will execute after the target. Optionally set a gas price override in gwei. Choose the execution method (backrunTransaction, submitBackrunBundle, or executeWithMevGeth). The tool fetches current gas price and base fee from the pending state. Once confirmed, it submits the backrun transaction, placing it behind the target in the block order. The tool simulates the backrun first to estimate success before submission.

TECHNICAL MECHANISM

Unlike standard transaction tools, this executor is purpose-built for MEV backrunning workflows. It reads the current mempool state via eth_call with blockTag 'pending' to simulate the target and backrun transactions in sequence. The tool fetches fee data using getFeeData() to display current gas price and base fee for context. It builds the backrun transaction with the provided calldata and target contract, applying gas price overrides when specified. The tool supports different execution methods: backrunTransaction for direct submission, submitBackrunBundle for Flashbots-style bundle submission (target + backrun), and executeWithMevGeth for mev-geth compatible execution. It simulates the backrun using eth_call to verify it will succeed given the pending state. Gas costs are calculated using receipt.effectiveGasPrice for accurate post-EIP-1559 fee accounting. The tool displays the target and backrun calldata lengths for debugging.

WHAT IT CANNOT SEE

This tool cannot guarantee that the backrun opportunity will still be available at the time of execution due to block state changes and competition. It cannot predict the exact gas price required for inclusion, nor can it detect if the target transaction has already been included or reorganized. It also cannot guarantee that the backrun will be profitable after gas costs. The tool cannot detect if the target transaction has been replaced by a different transaction with a higher gas price, or if the mempool state changes between simulation and submission. It also cannot verify that the backrun calldata correctly captures the arbitrage opportunity.

PLEASE NOTE

This tool supports EVM-compatible chains. Backrunning is competitive and time-sensitive—execute quickly. The target transaction must still be pending in the mempool for the backrun to succeed. Use gas price overrides carefully; too high may reduce profitability, too low may result in non-inclusion. Simulation does not guarantee success but helps identify obvious failures. This tool does not generate strategies—it executes user-provided backrun calldata. For strategy discovery, use the Searcher Bundle Simulation Tool.