Event Listener Generator

WHAT IT DOES

Event Listener Generator lets you fetch and decode all historical event logs emitted by a contract. You provide the contract address, an event signature (e.g., Transfer(address,address,uint256)), and a block range, and the tool queries the chain for all matching logs. It automatically handles RPC block range limits by chunking requests and halving chunk size on failure (PLAYBOOK-C §5.1). The decoded event data is displayed in a clean table with links to block explorers. This is essential for developers auditing contract activity, tracking token transfers, monitoring governance votes, or analyzing any on-chain events. It reads the current network chain ID from your wallet provider to ensure queries are directed to the correct network.

HOW TO USE

Connect your wallet using the "Connect" button (required for RPC access). Select the target network (Ethereum Mainnet, Sepolia, Polygon, BSC, Arbitrum, Optimism, and testnets are supported). Enter the contract address, the event signature (e.g., Transfer(address,address,uint256)), and optionally a block range. If no block range is provided, the tool scans the most recent 10,000 blocks. Click "Listen for events" — the tool will fetch and decode all matching logs. Results are shown in a table with block numbers, transaction hashes, and decoded event data. The entire operation is read-only — no transactions are signed or sent.

TECHNICAL MECHANISM

The tool uses eth_getLogs with a filter for the contract address and the event signature's Keccak-256 hash (topic0). Because public RPC providers cap the block range per request (often 10,000 blocks), the tool automatically chunks the requested range into smaller segments. If a chunk fails due to range limits, it halves the chunk size and retries, backing off until successful (PLAYBOOK-C §5.1). This ensures the scan completes even on restrictive RPCs. Once logs are fetched, the tool uses ethers.js's Interface to decode the event data based on the provided signature. Indexed parameters (topics) and non-indexed parameters (data) are parsed and displayed in a human-readable format. The tool uses ethers.js v5.7.2 and the wallet's provider for all chain interactions.

WHAT IT CANNOT SEE

The tool cannot verify if the contract actually emits the specified event — if the signature is incorrect, it will return no results or decode incorrectly. It cannot validate the correctness of the event data or decode complex nested types beyond basic ABI decoding (e.g., arrays of structs, nested tuples). It is limited by RPC provider rate limits and eth_getLogs block range caps — very large ranges may be slow or fail on free RPCs. It cannot listen to events in real-time — only historical logs. It cannot detect events from non-indexed parameters efficiently, as filtering only works on indexed topics. It cannot fetch events from contracts that do not emit standard logs.

PLEASE NOTE

This tool is for educational and analytical purposes. For production use, consider using a dedicated indexing service like The Graph. The accuracy of the results depends on the correctness of the event signature and the completeness of the RPC logs. Always verify the event signature against the contract's ABI. The tool does not persist any data; all state is lost on page reload. EVM chains only.