Contract Event Monitor-and-Alert Tool

WHAT IT DOES

Contract Event Monitor-and-Alert Tool is a read-only developer tool that monitors and detects events emitted by EVM smart contracts. It reads contract logs via eth_getLogs with a robust chunked fetching strategy that automatically halves block ranges when RPC providers reject full-range requests, ensuring complete event coverage even with provider-specific limitations. The tool decodes event data using contract ABIs, displays decoded events with their arguments, transaction hashes, and block numbers, and includes an alert stub for notification integration. It helps developers monitor contract activity, detect critical events (Transfers, Approvals, custom events), and build awareness of on-chain contract interactions without running a full node.

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, optionally specify an event name to filter by (e.g., Transfer, Approval), and set the block range to scan (100-10,000 blocks). Click "Monitor Events" to fetch and decode events from the specified range. Results include a summary of total events found, a detailed table of decoded events with transaction hashes, block numbers, and event arguments, and an alert stub indicating which events would trigger notifications. The tool uses chunked log fetching to handle RPC provider limits automatically. All analysis is read-only—no signatures or transactions are submitted.

TECHNICAL MECHANISM

The tool uses ethers.js v5.7.2 to fetch contract logs via the provider. The core mechanism is the chunked log fetching function (fetchLogsChunked) that handles provider-specific eth_getLogs limits. It starts with the full requested block range; if the provider rejects the request (typically due to response size limits), it halves the range and recursively fetches both halves. This continues until the request succeeds or a single block request fails. This approach ensures the tool works with major RPC providers (Alchemy, Infura, QuickNode, Ankr) that have different block range limits. The tool generates a mock ABI for common events (Transfer, Approval) and decodes logs using ethers.js Interface and parseLog methods. If an event name is specified, the tool filters logs using the event's topic signature. Results are displayed in a structured table with event names, transaction hashes (truncated), block numbers, and decoded arguments. The alert stub provides a placeholder for integration with external notification systems.

WHAT IT CANNOT SEE

This tool has fundamental limitations that users must understand. It cannot actually send alerts or notifications—the tool provides an alert stub but requires external infrastructure (email, Slack, Discord, etc.) for actual notifications. It cannot monitor events in real-time without continuous polling—the tool performs one-time scans and does not maintain a persistent connection. It cannot guarantee detection of all events if RPC providers have data gaps—historical data may be incomplete on some providers. It cannot handle events from contracts that are not ABI-verified—the tool relies on event signatures to decode logs. It cannot filter events by complex criteria beyond basic parameter matching—the tool can filter by event name but not by specific parameter values. It cannot monitor events across multiple chains simultaneously—only one contract on one network at a time. It cannot alert on events that occur between poll intervals—the tool only scans specified block ranges. It cannot detect events that are not standard ERC-20/ERC-721 events without custom ABI input. It cannot replay missed events if the RPC provider has gaps in historical data.

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. For production alerting, integrate the tool's output with external notification systems.