Historical Block Replay Tool

WHAT IT DOES

Historical Block Replay Tool is an analytics-focused utility that fetches and displays complete historical block data from any EVM-compatible chain. It retrieves full block details via eth_getBlockByNumber, including block hash, parent hash, timestamp, gas used, gas limit, and base fee per gas. The tool fetches every transaction in the block along with their receipts via eth_getTransactionReceipt, displaying transaction status, gas used, contract creation addresses, and all emitted logs. It also reads historical contract bytecodes using eth_getCode with block tag and historical storage state via eth_getStorageAt with block tag, enabling deep forensic analysis of contract behavior at any past block height. The tool supports log queries via eth_getLogs with block ranges and decodes contract ABIs where available. All data is presented in a structured, readable format with transaction counts, success/failure breakdowns, and detailed logs for each transaction.

HOW TO USE

Connect your wallet to the target EVM chain. Enter a block number into the input field and click "Fetch block". The tool will retrieve the block data from the RPC provider and display: block summary with hash, parent hash, timestamp, gas metrics, and transaction count; a list of all transactions with their status indicators (success/failed), from/to addresses, value transferred, gas used, and deployed contract addresses if any; and a sample of logs emitted by each transaction. The tool also indicates whether archival data is available for the requested block. Results are read-only and do not require any transaction signing.

TECHNICAL NOTE: ETH_GETLOGS CHUNKING AND BACKOFF

The tool implements a robust log fetching strategy that chunks block ranges automatically to handle RPC provider limits. When fetching logs from a block range, the tool starts with a default chunk size and halves it on each RPC refusal or timeout, backing off exponentially with jitter to avoid rate limiting. This ensures log scans complete even on public RPCs with aggressive caps. The tool also caches block and transaction data per session to avoid redundant RPC calls. For each transaction, the tool fetches the full receipt including logs and status, and decodes common log topics when possible. The tool uses eth_getCode with explicit block tags to retrieve contract bytecode at the historical block height, enabling analysis of contracts that may have been self-destructed or upgraded since. Storage state is queried via eth_getStorageAt with block tags to read historical values from specific storage slots.

WHAT IT CANNOT SEE

The tool cannot replay transactions that require off-chain dependencies or oracles, as those data sources are not available in historical snapshots. It cannot simulate contract interactions that depend on external state not captured in the historical block, such as cross-chain data or off-chain governance votes. It cannot verify that replayed results match the original execution if block data is incomplete or if the RPC provider does not support archival queries. The tool cannot replay transactions on non-EVM chains. It is limited by the RPC provider's archival node capabilities; not all providers store full historical state for every block. The tool cannot replay pending transactions or mempool state. It cannot detect historical events that were not emitted as logs, such as internal transactions that did not produce log entries.

PLEASE NOTE

This tool is designed exclusively for EVM-compatible chains (Ethereum, Polygon, BSC, Arbitrum, Optimism, Avalanche C-Chain, etc.). It does not support non-EVM blockchains like Bitcoin, Solana, Cosmos, or Tron. Historical data availability depends on the RPC provider's archival node support. Some providers only keep full historical state for a limited number of recent blocks. The tool is read-only and does not submit any transactions. Always use a reliable archival RPC endpoint for accurate historical data. The tool provides no warranty of data completeness; users are responsible for verifying data from multiple sources when performing forensic analysis.