> ## Documentation Index
> Fetch the complete documentation index at: https://docs.moralis.com/llms.txt
> Use this file to discover all available pages before exploring further.

# How to Monitor Wallet Activity in Real Time

> Learn how to monitor wallet transactions in real time using the Moralis Streams API, including setting up webhook listeners for on-chain activity.

The [Streams API](https://moralis.io/streams/) enables you to stream real-time blockchain data to your application through webhooks. This tutorial focuses on monitoring wallet transactions as they happen on-chain.

Common use cases include:

* Web3 alerts (e.g. whale alerts monitoring)
* Real-time transaction and crypto wallet notifications
* Monitoring wallet balances

## Prerequisites

* A [Moralis account](https://admin.moralis.io) with an API key
* Node.js or Python installed
* A webhook URL (you can use [https://webhook.site](https://webhook.site) for testing)

## Step 1: Install the Moralis SDK

Install the Moralis SDK for your preferred language:

```bash npm theme={null}
npm install moralis @moralisweb3/common-evm-utils
```

```bash yarn theme={null}
yarn add moralis @moralisweb3/common-evm-utils
```

```bash pip theme={null}
pip install moralis
```

## Step 2: Create a Stream to Monitor Wallet Transactions

Once you have your API key and webhook URL, set up a stream to monitor on-chain wallet transactions. In this example, we will monitor the address `0x68b3f12d6e8d85a8d3dbbc15bba9dc5103b888a4`.

**JavaScript:**

```javascript index.js theme={null}
const Moralis = require("moralis").default;
const { EvmChain } = require("@moralisweb3/common-evm-utils");

const runApp = async () => {
  await Moralis.start({
    apiKey: "YOUR_API_KEY",
  });

  const stream = {
    chains: [EvmChain.ETHEREUM, EvmChain.POLYGON],
    description: "monitor Bobs wallet",
    tag: "bob",
    webhookUrl: "https://YOUR_WEBHOOK_URL",
    includeNativeTxs: true,
  };

  const newStream = await Moralis.Streams.add(stream);
  const { id } = newStream.toJSON();

  // Now we attach bobs address to the stream
  const address = "0x68b3f12d6e8d85a8d3dbbc15bba9dc5103b888a4";

  await Moralis.Streams.addAddress({ address, id });
};

runApp();
```

**TypeScript:**

```typescript index.ts theme={null}
import Moralis from "moralis";
import { EvmChain } from "@moralisweb3/common-evm-utils";

const runApp = async () => {
  await Moralis.start({
    apiKey: "YOUR_API_KEY",
  });

  const stream = {
    chains: [EvmChain.ETHEREUM, EvmChain.POLYGON],
    description: "monitor Bobs wallet",
    tag: "bob",
    webhookUrl: "https://YOUR_WEBHOOK_URL",
    includeNativeTxs: true,
  };

  const newStream = await Moralis.Streams.add(stream);
  const { id } = newStream.toJSON();

  // Now we attach bobs address to the stream
  const address = "0x68b3f12d6e8d85a8d3dbbc15bba9dc5103b888a4";

  await Moralis.Streams.addAddress({ address, id });
};

runApp();
```

**Python:**

```python index.py theme={null}
from moralis import streams

api_key = "YOUR_API_KEY"

create_stream_body = {
  "description": "monitor Bobs wallet",
  "tag": "bob",
  "webhook_url": "https://YOUR_WEBHOOK_URL",
  "include_native_txs": True,
  "chain_ids": [
    "0x1",
    "0x89"
  ]
}

result = streams.evm_streams.create_stream(
  api_key=api_key,
  body=create_stream_body,
)

add_address_body = {
  "address": "0x68b3f12d6e8d85a8d3dbbc15bba9dc5103b888a4"
}

params = {
  "id": result.id
}

# Now we attach bobs address to the stream
streams.evm_streams.add_address_to_stream(
  api_key=api_key,
  body=add_address_body,
  params=params,
)
```

Once the code has been added, run the script to create the stream. This will be reflected on your Moralis Dashboard as well. From here, you will receive new real-time responses on your attached webhook for any new transactions occurring on either Ethereum or Polygon.

## Step 3: Listen to Smart Contract Events

In addition to monitoring wallet transactions in real-time, you can use Streams to listen to smart contract events whenever they are emitted on the blockchain.

For example, to listen to all ERC20 transfers for [USDT](https://etherscan.io/token/0xdac17f958d2ee523a2206206994597c13d831ec7):

**JavaScript:**

```javascript index.js theme={null}
const Moralis = require("moralis").default;
const { EvmChain } = require("@moralisweb3/common-evm-utils");

const ERC20_transfer_ABI = [
  {
    anonymous: false,
    inputs: [
      { indexed: true, name: "from", type: "address" },
      { indexed: true, name: "to", type: "address" },
      { indexed: false, name: "value", type: "uint256" },
    ],
    name: "Transfer",
    type: "event",
  },
];

const runApp = async () => {
  await Moralis.start({
    apiKey: "YOUR_API_KEY",
  });

  const stream = {
    chains: [EvmChain.ETHEREUM],
    description: "monitor USDT transfers",
    tag: "USDT",
    webhookUrl: "https://YOUR_WEBHOOK_URL",
    abi: ERC20_transfer_ABI,
    includeContractLogs: true,
    topic0: ["Transfer(address,address,uint256)"],
  };

  const newStream = await Moralis.Streams.add(stream);
  const { id } = newStream.toJSON();

  // Now we attach USDT address to the stream
  const address = "0xdAC17F958D2ee523a2206206994597C13D831ec7";

  await Moralis.Streams.addAddress({ address, id });
};

runApp();
```

**Python:**

```python index.py theme={null}
from moralis import streams

api_key = "YOUR_API_KEY"

ERC20_transfer_ABI = [{
  "anonymous": False,
  "inputs": [
    { "indexed": True, "name": "from", "type": "address" },
    { "indexed": True, "name": "to", "type": "address" },
    { "indexed": False, "name": "value", "type": "uint256" },
  ],
  "name": "Transfer",
  "type": "event",
}]

create_stream_body = {
  "description": "monitor USDT transfers",
  "tag": "USDT",
  "webhook_url": "https://YOUR_WEBHOOK_URL",
  "include_contract_logs": True,
  "chain_ids": [
    "0x1"
  ],
  "abi": ERC20_transfer_ABI,
  "topic0": ["Transfer(address,address,uint256)"]
}

result = streams.evm_streams.create_stream(
  api_key=api_key,
  body=create_stream_body,
)

add_address_body = {
  "address": "0xdAC17F958D2ee523a2206206994597C13D831ec7"
}

params = {
  "id": result.id
}

# Now we attach USDT address to the stream
streams.evm_streams.add_address_to_stream(
  api_key=api_key,
  body=add_address_body,
  params=params,
)
```

## Step 4: Add Filters for Specific Use Cases

For listening to smart contracts, you can add the [Filters feature](/streams/streams-concepts/filters) to filter out results that only fulfill certain criteria. This is useful for specific use cases such as whale monitoring.

For example, to monitor all USDT transactions on Ethereum over \$1M:

**JavaScript:**

```javascript index.js theme={null}
const filter_ERC20 = {
  "and": [
    { "eq": ["from", "0x283af0b28c62c092c9727f1ee09c02ca627eb7f5"] },
    { "gt": ["value", "1000000000"] }, // Example of USDT (6 Decimals)
  ],
};

const runApp = async () => {
  const stream = {
    // same parameters as prior
    advancedOptions: [
      {
        topic0: "Transfer(address,address,uint256)",
        filter: filter_ERC20
      },
    ]
  };

  const newStream = await Moralis.Streams.add(stream);
  const { id } = newStream.toJSON();

  // Now we attach USDT address to the stream
  const address = "0xdAC17F958D2ee523a2206206994597C13D831ec7";

  await Moralis.Streams.addAddress({ address, id });
};

runApp();
```

**Python:**

```python index.py theme={null}
filter_ERC20 = {
  "and": [
    { "eq": ["from", "0x283af0b28c62c092c9727f1ee09c02ca627eb7f5"] },
    { "gt": ["value", "1000000000"] },  # Example of USDT (6 Decimals)
  ],
}

create_stream_body = {
  # same parameters as prior
  "advanced_options": [
    {
      "topic0": "Transfer(address,address,uint256)",
      "filter": filter_ERC20
    }
  ]
}

result = streams.evm_streams.create_stream(
  api_key=api_key,
  body=create_stream_body,
)

add_address_body = {
  "address": "0xdAC17F958D2ee523a2206206994597C13D831ec7"
}

params = {
  "id": result.id
}

# Now we attach USDT address to the stream
streams.evm_streams.add_address_to_stream(
  api_key=api_key,
  body=add_address_body,
  params=params,
)
```

Once modified, you will only receive USDT transfers on Ethereum over \$1M in real-time on your webhooks.