> 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/cosmos/subscribe-cosmos.md).

# subscribe - Cosmos

Subscribes to events matching a Tendermint event query over WebSocket. Use queries like `tm.event='NewBlock'`, `tm.event='Tx'`, or `transfer.recipient='cosmos1...'`. Returns a subscription that streams matching events as separate WebSocket messages.

{% hint style="info" %}
**WebSocket-only method.** This method is only available over the WebSocket transport at `wss://go.getblock.io/<ACCESS-TOKEN>/websocket`. It will not work via HTTP POST. Use a WebSocket client such as wscat, the @cosmjs/tendermint-rpc WebSocketClient, or Python's websockets library.
{% endhint %}

## Parameters

| Parameter | Type   | Required | Description                   |
| --------- | ------ | -------- | ----------------------------- |
| query     | string | Yes      | Tendermint event query string |

## Request Example

{% tabs %}
{% tab title="cURL" %}

```bash
# WebSocket-only method. Use wscat (or similar) to connect first:
wscat -c 'wss://go.getblock.io/<ACCESS-TOKEN>/websocket'

# Then send:
{"jsonrpc": "2.0", "method": "subscribe", "params": {"query": "tm.event='NewBlock'"}, "id": "getblock.io"}
```

{% endtab %}

{% tab title="JavaScript (Axios)" %}

```javascript
import WebSocket from 'ws';

const ws = new WebSocket('wss://go.getblock.io/<ACCESS-TOKEN>/websocket');

ws.on('open', () => {
    ws.send(JSON.stringify({
    "jsonrpc": "2.0",
    "method": "subscribe",
    "params": {
        "query": "tm.event='NewBlock'"
    },
    "id": "getblock.io"
}));
});

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

{% endtab %}

{% tab title="Python (Requests)" %}

```python
import asyncio
import json
import websockets

async def main():
    async with websockets.connect('wss://go.getblock.io/<ACCESS-TOKEN>/websocket') as ws:
        await ws.send(json.dumps({
    "jsonrpc": "2.0",
    "method": "subscribe",
    "params": {
        "query": "tm.event='NewBlock'"
    },
    "id": "getblock.io"
}))
        async for message in ws:
            print(json.loads(message))

asyncio.run(main())
```

{% endtab %}

{% tab title="Rust (Reqwest)" %}

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

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let (mut ws_stream, _) = connect_async("wss://go.getblock.io/<ACCESS-TOKEN>/websocket").await?;

    let payload = json!({
        "jsonrpc": "2.0",
        "method": "subscribe",
        "params": {
                "query": "tm.event='NewBlock'"
        },
        "id": "getblock.io"
});
    ws_stream.send(Message::Text(payload.to_string())).await?;

    while let Some(msg) = ws_stream.next().await {
        println!("{:?}", msg?);
    }
    Ok(())
}
```

{% endtab %}
{% endtabs %}

## Response Example

{% code overflow="wrap" %}

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

{% endcode %}

## Response Parameters

| Field  | Type   | Description                                                                     |
| ------ | ------ | ------------------------------------------------------------------------------- |
| result | object | Empty object on success — streamed events arrive as separate WebSocket messages |

## Use Cases

* Real-time block notifications (`tm.event='NewBlock'`)
* Live transaction streaming (`tm.event='Tx'`)
* Per-account activity feeds (`transfer.recipient='cosmos1...'`)
* IBC packet flow monitoring
* Governance event tracking

## Error Handling

| Status Code | Error Message               | Cause                                                                    |
| ----------- | --------------------------- | ------------------------------------------------------------------------ |
| 404         | Not Found                   | Missing or invalid `<ACCESS-TOKEN>`                                      |
| -32602      | Invalid params              | Request parameters are missing or malformed                              |
| -32603      | Internal error              | Server-side error while processing the request                           |
| 429         | Too Many Requests           | Rate limit exceeded for your plan                                        |
| -32603      | Subscription limit exceeded | Each WebSocket connection has a maximum subscription count (typically 5) |
| -32602      | Invalid query               | Query string is malformed or references unknown event types              |

## SDK Integration

{% tabs %}
{% tab title="CosmJS" %}

```javascript
import { Tendermint37Client, WebsocketClient } from '@cosmjs/tendermint-rpc';

const wsClient = new WebsocketClient('wss://go.getblock.io/<ACCESS-TOKEN>/websocket');
const client = await Tendermint37Client.create(wsClient);

// Use the typed subscription methods on the client where available.
// For raw subscription access:
const stream = wsClient.listen({"jsonrpc": "2.0", "id": "sub-1", "method": "subscribe", "params": {"query": "tm.event='NewBlock'"}});
stream.subscribe({
    next: (event) => console.log(event),
    error: (err) => console.error(err)
});
```

{% endtab %}

{% tab title="cosmpy / websockets" %}

```python
# cosmpy does not expose CometBFT WebSocket subscriptions directly.
# Use the `websockets` library as shown in the Request Example above.
import asyncio
import json
import websockets

async def stream():
    async with websockets.connect('wss://go.getblock.io/<ACCESS-TOKEN>/websocket') as ws:
        await ws.send(json.dumps({'jsonrpc': '2.0', 'id': 'sub-1', 'method': 'subscribe', 'params': {"query": "tm.event='NewBlock'"}}))
        async for msg in ws:
            print(json.loads(msg))

asyncio.run(stream())
```

{% endtab %}
{% endtabs %}


---

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