> For the complete documentation index, see [llms.txt](https://capsurelabs.gitbook.io/technical-documentation-1/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://capsurelabs.gitbook.io/technical-documentation-1/wallet-management-and-monitoring/transaction-and-balance-monitoring-tools.md).

# Transaction and Balance Monitoring Tools

## 1.1 T\&B Monitoring Overview

{% hint style="info" %}
Transaction and Balance Monitoring Tools in the CapsureLabs platform allow users to track real-time wallet activity, including balance updates and transaction histories. These tools are designed to support both Ethereum-compatible blockchains and can be extended to support additional chains. This documentation provides code examples using Web3.js to monitor balances and transactions efficiently.
{% endhint %}

***

## 1.2 Code for Monitoring Balances and Transactions

### 1.2.1 Monitoring Wallet Balance

```javascript
const Web3 = require('web3');
const web3 = new Web3('wss://mainnet.infura.io/ws/v3/YOUR_INFURA_PROJECT_ID');

// Define the user's wallet address
const walletAddress = '0xYourEthereumAddressHere';

// Function to retrieve the current balance
async function checkBalance() {
  try {
    const balance = await web3.eth.getBalance(walletAddress);
    console.log(`Wallet Balance: ${web3.utils.fromWei(balance, 'ether')} ETH`);
  } catch (error) {
    console.error("Error fetching balance:", error);
  }
}

// Check balance at regular intervals (e.g., every minute)
setInterval(checkBalance, 60000);
```

### 1.2.2 Real-Time Balance Monitoring with WebSocket

```javascript
web3.eth.subscribe('newBlockHeaders', (error, block) => {
  if (error) console.error("Subscription error:", error);
  else checkBalance();
});
```

### 1.2.3 Transaction Monitoring

```javascript
const monitoredAddress = walletAddress;

// Function to monitor new transactions in each block
web3.eth.subscribe('pendingTransactions', async (error, txHash) => {
  if (error) return console.error("Error:", error);

  // Get transaction details
  const tx = await web3.eth.getTransaction(txHash);

  if (tx && (tx.to === monitoredAddress || tx.from === monitoredAddress)) {
    console.log("Transaction detected:");
    console.log(`From: ${tx.from}`);
    console.log(`To: ${tx.to}`);
    console.log(`Amount: ${web3.utils.fromWei(tx.value, 'ether')} ETH`);
    console.log(`Tx Hash: ${tx.hash}`);
  }
});
```

### 1.2.4 **Multi-Asset Balance Monitoring (ERC-20 Tokens)**

```javascript
const tokenContractAddress = '0xTokenContractAddressHere';
const tokenABI = [
  // Minimal ABI to get balance
  {
    "constant": true,
    "inputs": [{ "name": "_owner", "type": "address" }],
    "name": "balanceOf",
    "outputs": [{ "name": "balance", "type": "uint256" }],
    "type": "function"
  }
];

// Create contract instance
const tokenContract = new web3.eth.Contract(tokenABI, tokenContractAddress);

// Function to check token balance
async function checkTokenBalance() {
  try {
    const tokenBalance = await tokenContract.methods.balanceOf(walletAddress).call();
    console.log(`Token Balance: ${web3.utils.fromWei(tokenBalance, 'ether')} Tokens`);
  } catch (error) {
    console.error("Error fetching token balance:", error);
  }
}

// Check token balance periodically
setInterval(checkTokenBalance, 60000);
```

***

## 1.3 API Integration

### 1.3.1 GET /wallets/{wallet\_id}/balance

```bash
curl -X GET "https://api.capsurelabs.com/wallets/0xYourWalletAddress/balance" \
  -H "Authorization: Bearer <token>"
```

### 1.3.2 GET /wallets/{wallet\_id}/transactions

```bash
curl -X GET "https://api.capsurelabs.com/wallets/0xYourWalletAddress/transactions" \
  -H "Authorization: Bearer <token>"
```

### 1.3.3 WebSocket /wallets/subscribe

```json
{
  "type": "subscribe",
  "walletId": "0xYourWalletAddress"
}
```