ChainWatcher

Decentralized, real-time wallet tracker for Ethereum-VM chains

Overview

ChainWatcher lets you monitor any Ethereum-compatible wallet—Ethereum, Binance Smart Chain, Arbitrum, and more—in one clean dashboard.

The user can add the addresses they care about, and get instant browser notifications as soon as on-chain events happen.

Dark mode, custom accent colors, responsive layout—everything adapts to your tastes and screen size.

My Role

• Sole planner, architect, and developer
• Drafted feature list and prioritized the MVP
• Built a clickable prototype for user feedback
• Iterated on performance, reliability, and UX
• Rolled the app out to production and monitored real traffic

Tech Stack

• Frontend: React, Tailwind CSS, React Context API (API & UI contexts), Socket.io client, Ethers.js
• Backend: Node.js, Express, MongoDB (Mongoose), Socket.io server
• Blockchain data: public RPC endpoints (Infura, Alchemy, BSC RPC), Etherscan-style APIs for metadata and internal transactions

How It Works

1. User registers and adds wallet addresses.
2. Backend polls or subscribes via WebSocket to each chain’s RPC endpoint, enriching raw TX data via a scanner API.
3. New events are stored in MongoDB (users, wallets, notifications, error logs) and pushed to connected clients via Socket.io.
4. On the frontend, APIContext manages REST calls, sockets, and blockchain connections. AppStateContext handles UI preferences—dark mode, sidebar toggles, toast messages, custom colors, and screen-size flags. Components use local useState hooks for internal state.

Key Features

• Real-time transaction alerts (incoming, outgoing, token transfers, contract events)
• Multi-chain support—track wallets across any Ethereum-VM network
• Custom filters by value, token type, or contract address
• Fully themeable UI with dark/light modes and accent-color picker
• Resilient error handling and auto-reconnect for RPC and socket failures

Challenges & Solutions

• Polling vs. subscriptions: Use WebSocket subscriptions when available; fallback to light polling (every 10 s).
• State sprawl: Split concerns into API and UI contexts to keep components focused.
• Event flooding: Batch DB writes and debounce socket pushes to prevent user spam during high-traffic periods.

Outcome & Learnings

ChainWatcher is now a stable, production-ready dApp used by early adopters to monitor dozens of wallets in real time.

I deepened my expertise in Ethereum tooling (Ethers.js, RPC/WebSocket patterns), real-time communication (Socket.io), and clean state management with React Context. The modular architecture makes adding new chains straightforward.