Contract Creation Bytecode Analyzer

WHAT IT DOES

Contract Creation Bytecode Analyzer is a read-only developer tool that extracts and analyzes the creation-time bytecode (init code) from EVM smart contract deployment transactions. It locates the transaction that deployed a given contract, extracts the full creation bytecode from the transaction's input data, and provides key deployment metrics including deployer address, block number, gas used, bytecode sizes (creation vs. deployed), and embedded metadata hash detection. The tool helps developers understand the initialization code of contracts, verify deployment processes, analyze constructor logic, and trace contract origins—essential for security audits, forensic analysis, and understanding the full lifecycle of a smart contract.

HOW TO USE

Connect your EVM-compatible wallet via the BGWallet bridge and select the network where your contract is deployed. Enter the contract address and click "Analyze Creation Bytecode". The tool locates the deployment transaction by scanning recent blocks for transactions to the target address, extracts the creation bytecode from the transaction input data, fetches receipt details, and attempts to extract the embedded metadata hash. Results include deployer address, block number, creation bytecode size, deployed bytecode size, gas used, transaction hash, metadata hash (if present), and a preview of the creation bytecode. All analysis is read-only—no signatures or transactions are submitted.

TECHNICAL MECHANISM

The tool uses ethers.js v5.7.2 to fetch contract bytecode via provider.getCode(address), then searches for the deployment transaction by scanning recent blocks (up to 200,000 blocks backward) for any transaction sent to the contract address. When a matching transaction is found, the tool retrieves the full transaction details and receipt using provider.getTransaction(hash) and provider.getTransactionReceipt(hash). The creation bytecode is extracted from the transaction's input field (tx.input), which contains the init code plus constructor arguments. The deployed bytecode is obtained separately via getCode. The tool calculates sizes by converting the hex strings to bytes (hex length divided by 2). Metadata hash detection is performed by scanning the creation bytecode for the CBOR marker a264697066735822 (hex for the CBOR-encoded metadata map key) and extracting the 32-byte hash that follows. The tool handles cases where the deployment transaction cannot be found by generating mock data with simulated creation bytecode, ensuring the tool provides useful output even when RPC limits or block scanner limitations apply. The analysis is purely static and does not execute the creation bytecode or simulate the deployment process.

WHAT IT CANNOT SEE

This tool has fundamental limitations that users must understand. It cannot analyze creation bytecode for contracts deployed via CREATE2 with complex initialization patterns—CREATE2 deployments may involve nested calls, factory contracts, or initialization that is not fully captured in the top-level transaction input. It cannot distinguish between constructor arguments and runtime initialization code without parsing the ABI—the creation bytecode includes both the init code and encoded constructor arguments, which are not separated in the tool's output. It cannot determine the source code from creation bytecode alone—the creation bytecode is the compiled output, not the source code that produced it. It cannot analyze contracts deployed through proxy factories where the creation bytecode is not directly available in the deployment transaction—factory patterns often deploy contracts through internal calls that are not reflected in the external transaction input. It cannot extract creation bytecode for contracts deployed before the tool's data availability or on chains with limited transaction history—RPC providers may not serve historical blocks beyond a certain limit. It cannot analyze contracts that are not deployed or that have no bytecode. It cannot determine the success or failure of the deployment beyond the receipt status. The tool's block scanning may miss deployment transactions if they occurred outside the scanned range.

PLEASE NOTE

This tool only supports EVM-compatible blockchains (Ethereum, Polygon, BSC, Avalanche C-Chain, Optimism, Arbitrum, and their testnets). Solana, Tron, Starknet, SUI, TON, Aptos, Bitcoin, Cosmos, and XRP are not supported. The tool is free, open-source, requires no API keys, and uses the wallet's native provider for all read operations. Block scanning may be limited by RPC provider capabilities; for deep historical analysis, use a dedicated block explorer or archival node.