Fund Sentinel 🛡️

Multi-chain wallet balance monitoring with threshold alerts. Tracks ETH and token balances across Base and Ethereum networks, comparing against historical snapshots to detect suspicious activity.

Features

• Multi-chain monitoring: Base and Ethereum mainnet
• Token support: Native ETH + ERC20 tokens (USDC, WETH, etc.)
• Threshold alerts: Configurable balance drop percentages
• Historical tracking: Maintains snapshot history with timestamps
• RPC-based: Direct blockchain queries using viem (no API keys needed)
• JSON output: Machine-readable alerts and balance data

Quick Start

1. Install dependencies:

   npm install
   

2. Create config file:

   cp config.example.json config.json
   # Edit config.json with your wallets and thresholds
   

3. Run monitor:

   node sentinel.mjs
   # or
   ./scripts/run.sh
   

Configuration

Edit config.json with your settings:

{
  "wallets": {
    "treasury": "0x...",
    "main": "0x..."
  },
  "thresholds": {
    "balanceDropPercent": 20,    // Alert if balance drops >20%
    "minAlertValueUsd": 100      // Only alert if drop >$100 value
  }
}

Output Format

Success (Exit code 0)

{
  "timestamp": "2026-02-09T20:45:00Z",
  "alerts": [],
  "snapshot": {
    "treasury": {
      "base": { "ETH": "0.11", "USDC": "1250.50" },
      "ethereum": { "ETH": "0.05", "USDC": "500.00" }
    }
  },
  "changes": [...]
}

Alerts Detected (Exit code 1)

{
  "timestamp": "2026-02-09T20:45:00Z",
  "alerts": [
    {
      "severity": "HIGH",
      "wallet": "treasury",
      "chain": "base",
      "token": "USDC",
      "previousBalance": "4700.00",
      "currentBalance": "0.00",
      "changePercent": -100,
      "message": "⚠️ treasury USDC on base dropped 100% (4700.00 → 0.00)"
    }
  ],
  "snapshot": {...}
}

Cron Integration

Add to your crontab for automated monitoring:

# Check every 15 minutes
*/15 * * * * cd /path/to/fund-sentinel && ./scripts/run.sh >> /var/log/fund-sentinel.log 2>&1

# Email on alerts (requires mail setup)
*/15 * * * * cd /path/to/fund-sentinel && ./scripts/run.sh | jq -r '.alerts[] | .message' | mail -s "Fund Alert" admin@domain.com

Alert Severities

• HIGH: Balance dropped >50% or significant value lost
• MEDIUM: Balance dropped >threshold% but <50%
• LOW: Minor changes within normal range

Supported Networks

• Base (chainId: 8453)

  • Native ETH
  • USDC: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
  • WETH: 0x4200000000000000000000000000000000000006

• Ethereum (chainId: 1)

  • Native ETH
  • USDC: 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
  • WETH: 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2

Exit Codes

• 0: No alerts detected
• 1: Alerts detected (check output JSON)
• 2: Error occurred (config, network, etc.)

Files

• sentinel.mjs: Main monitoring script
• config.json: Your wallet/threshold configuration
• snapshots.json: Historical balance data (auto-generated)
• scripts/run.sh: Wrapper script with exit code handling

Troubleshooting

Network errors: Check RPC endpoint availability Permission errors: Ensure write access for snapshots.json Memory issues: Large multicall batches may need chunking

Security Notes

• Config file contains wallet addresses (not private keys)
• Uses public RPC endpoints - no authentication required
• Snapshots contain historical balance data - protect accordingly