> For the complete documentation index, see [llms.txt](https://docs.getblock.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.getblock.io/api-reference/polygon-matic/polygon-json-rpc-api/matic_eth_subscribe.md).

# eth\_subscribe - Polygon

The **eth\_subscribe** method creates a subscription over WebSocket to receive real-time notifications for new blocks, pending transactions, or logs matching specified criteria.

{% hint style="info" %}
This method requires a WebSocket connection.
{% endhint %}

## Parameters

| Parameter        | Type   | Required | Description                                                     |
| ---------------- | ------ | -------- | --------------------------------------------------------------- |
| subscriptionType | string | Yes      | Subscription type: "newHeads", "newPendingTransactions", "logs" |
| filterObject     | object | No       | Filter options for log subscriptions                            |

## Request

{% tabs %}
{% tab title="cURL" %}
{% code title="cURL (wscat)" overflow="wrap" %}

```bash
# This method requires WebSocket connection
wscat -c wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/

> {"jsonrpc":"2.0","method":"eth_subscribe","params":["newheads"],"id":"getblock.io"}
```

{% endcode %}
{% endtab %}

{% tab title="Javascript" %}
{% code title="JavaScript (ws)" %}

```javascript
const WebSocket = require('ws');

const ws = new WebSocket('wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

ws.on('open', () => {
    ws.send(JSON.stringify({
        jsonrpc: '2.0',
        method: 'eth_subscribe',
        params: ['newHeads'],
        id: 'getblock.io'
    }));
});

ws.on('message', (data) => {
    console.log(JSON.parse(data));
});
```

{% endcode %}
{% endtab %}

{% tab title="Python" %}
{% code title="Python (websockets)" %}

```python
import asyncio
import websockets
import json

async def unsubscribe():
    uri = "wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/"
    async with websockets.connect(uri) as ws:
        payload = {
            "jsonrpc": "2.0",
            "method": "eth_subscribe",
            "params": ["newHeads"],
            "id": "getblock.io"
        }
        await ws.send(json.dumps(payload))
        response = await ws.recv()
        print(json.loads(response))

asyncio.run(unsubscribe())
```

{% endcode %}
{% endtab %}

{% tab title="Rust" %}
{% code title="Rust (tokio-tungstenite)" %}

```rust
use tokio_tungstenite::connect_async;
use futures_util::{SinkExt, StreamExt};
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let url = "wss://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/";
    let (mut ws, _) = connect_async(url).await?;
    
    let payload = json!({
        "jsonrpc": "2.0",
        "method": "eth_subscribe",
        "params": ["newHeads"],
        "id": "getblock.io"
    });
    
    ws.send(payload.to_string().into()).await?;
    
    if let Some(msg) = ws.next().await {
        println!("{:?}", msg?);
    }
    
    Ok(())
}
```

{% endcode %}
{% endtab %}
{% endtabs %}

## Response

```json
{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x9cef478923ff08bf67fde6c64013158d"
}
```

## Response Parameters

| Field   | Type   | Description                                 |
| ------- | ------ | ------------------------------------------- |
| jsonrpc | string | JSON-RPC version (2.0)                      |
| id      | string | Request identifier                          |
| result  | varies | Subscription ID for receiving notifications |

## Use Case

The eth\_subscribe method is useful for:

* **Real-time block monitoring**
* **Event streaming**
* **Live transaction tracking**

## Error Handling

| Status Code | Error Message   | Cause                           |
| ----------- | --------------- | ------------------------------- |
| 403         | Forbidden       | Missing or invalid ACCESS-TOKEN |
| -32600      | Invalid Request | Malformed request body          |
| -32602      | Invalid params  | Invalid method parameters       |

## Web3 Integration

{% tabs %}
{% tab title="Ethers.js" %}
{% code title="ethers.js example" %}

```javascript
import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

const result = await provider.send('eth_subscribe', ["newHeads"]);
console.log('Result:', result);
```

{% endcode %}
{% endtab %}

{% tab title="Viem" %}
{% code title="viem example" %}

```javascript
import { createPublicClient, http } from 'viem';
import { polygon } from 'viem/chains';

const client = createPublicClient({
    chain: polygon,
    transport: http('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/')
});

const result = await client.request({
    method: 'eth_subscribe',
    params: ["newHeads"]
});
console.log('Result:', result);
```

{% endcode %}
{% endtab %}
{% endtabs %}