WebSocket Subscription Manager for Contract Events

WHAT IT DOES

WebSocket Subscription Manager for Contract Events lets you subscribe to real-time contract events via WebSocket RPC connections. You provide a WebSocket RPC URL and contract address, optionally specify an event name or topic filters, and the tool establishes a persistent WebSocket connection. It subscribes to the contract's event logs using eth_subscribe, displays active subscriptions with their IDs, and streams incoming events in real-time. Each event is shown with a timestamp, the contract address, topics, and data preview. The tool also shows connection status, subscription count, and total events received. This is essential for developers monitoring on-chain activity, building real-time dashboards, tracking NFT mints, detecting transaction events, or any application that needs live blockchain data without polling.

HOW TO USE

Enter your WebSocket RPC URL (e.g., wss://mainnet.infura.io/ws/v3/YOUR_KEY). Enter the contract address you want to monitor. Optionally specify an event name (e.g., "Transfer") to filter events, or add topic filters as a comma-separated list of 0x-prefixed hashes. Click "Subscribe." The tool connects to the WebSocket endpoint, subscribes to the contract's logs, and begins streaming events. Active subscriptions are displayed with their IDs. Each incoming event appears in the event log with a timestamp and a preview of the log data. Use "Unsubscribe All" to close the connection and remove all subscriptions, or "Clear Events" to clear the event log without disconnecting. The tool maintains a rolling log of up to 500 events.

THE REAL MECHANISM

The tool uses ethers.js v5.7.2's WebSocketProvider to establish a WebSocket connection to the RPC endpoint. It creates a filter object with the contract address and optional topics, then subscribes using provider._subscribe('logs', filter). The subscription returns a subscription ID that is displayed in the UI. When an event is received, the provider emits a 'log' event, which the tool captures and formats for display. The event data includes the log's address, topics, data, block number, and transaction hash. The tool displays a formatted preview showing the address, first few topics, and a data preview. The WebSocket connection is maintained until manually unsubscribed or the page is closed. All event logs are stored in memory with timestamps. The tool does not persist any data across page reloads.

WHAT IT CANNOT SEE

This tool cannot automatically reconnect if the WebSocket connection drops—you must manually resubscribe. It cannot detect if the subscription is receiving events without manual verification—you must watch the event stream. It cannot generate subscriptions for non-EVM chains. It cannot monitor historical events via WebSocket—WebSocket subscriptions only provide real-time events from the moment of subscription. It cannot handle high-frequency event streams without risk of message overflow—very active contracts may generate more events than the UI can display comfortably. The tool does not decode event data into human-readable values—it displays raw hex data.

PLEASE NOTE

WebSocket Subscription Manager works exclusively with EVM-compatible chains that support WebSocket RPC endpoints. It requires a valid WebSocket RPC URL with the wss:// protocol. The tool does not send transactions or modify blockchain state. All data is processed client-side in your browser. The tool is free to use and does not require authentication. For best results, use WebSocket endpoints that support eth_subscribe and have sufficient rate limits for your use case.