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# Subscription Channels

The Paradex WebSocket API allows you to subscribe to various channels to receive real-time updates. This page explains how to subscribe and unsubscribe from channels.

## Subscribing to Channels

To receive updates from a specific channel, you need to subscribe to it. Multiple calls to subscribe can be made, each for a different channel.

**Note**: Subscribing to the same channel more than once will return an error.

### Subscribe Request

To subscribe to a channel, send a message with the following format:

```json
{
  "jsonrpc": "2.0",
  "method": "subscribe",
  "params": {
    "channel": "CHANNEL_NAME"
  },
  "id": 1
}
```

### Subscribe Parameters

| Parameter | Type   | Description  | Required |
| --------- | ------ | ------------ | -------- |
| channel   | string | Channel name | Yes      |

### Subscribe Response

Upon successful subscription, you will receive a response similar to:

```json
{
  "jsonrpc": "2.0",
  "result": {
    "channel": "CHANNEL_NAME"
  },
  "usIn": 1682556415569005368,
  "usDiff": 1291796,
  "id": 1
}
```

### Subscribe Response Parameters

| Parameter | Type   | Description  | Required |
| --------- | ------ | ------------ | -------- |
| channel   | string | Channel name | Yes      |

## Unsubscribing from Channels

To stop receiving updates from a specific channel, you need to unsubscribe from it.

**Note**: Unsubscribing from a channel that you are not subscribed to will return an error.

### Unsubscribe Request

To unsubscribe from a channel, send a message with the following format:

```json
{
  "jsonrpc": "2.0",
  "method": "unsubscribe",
  "params": {
    "channel": "CHANNEL_NAME"
  },
  "id": 2
}
```

### Unsubscribe Parameters

| Parameter | Type   | Description  | Required |
| --------- | ------ | ------------ | -------- |
| channel   | string | Channel name | Yes      |

### Unsubscribe Response

Upon successful unsubscription, you will receive a response similar to:

```json
{
  "jsonrpc": "2.0",
  "result": {
    "channel": "CHANNEL_NAME"
  },
  "usIn": 1682556415569005368,
  "usDiff": 1291796,
  "id": 2
}
```

### Unsubscribe Response Parameters

| Parameter | Type   | Description  | Required |
| --------- | ------ | ------------ | -------- |
| channel   | string | Channel name | Yes      |

## Example: Subscribing to a Channel

Public channel payloads are SBE binary frames, so a subscriber needs a decoder as well as a socket. The Paradex Python SDK handles both:

```python
import asyncio

from paradex_py.api.ws_client import ParadexWebsocketChannel, ParadexWebsocketClient
from paradex_py.environment import TESTNET


async def on_message(channel, message):
    print(channel, message["params"]["data"])


async def main():
    ws_client = ParadexWebsocketClient(env=TESTNET, sbe_enabled=True)
    await ws_client.connect()
    await ws_client.subscribe(
        ParadexWebsocketChannel.TRADES,
        callback=on_message,
        params={"market": "ETH-USD-PERP"},
    )
    await asyncio.sleep(30)


asyncio.run(main())
```

The subscribe request and its acknowledgement above are JSON-RPC text frames; the trade updates that follow are binary. See [Code Examples](/ws/general-information/code-examples) for authentication and unsubscribing, and [Binary Encoding (SBE)](/ws/general-information/binary-encoding-sbe) to generate a decoder in another language.

## Example: Unsubscribing from a Channel

```python
await ws_client.unsubscribe_by_name("trades.ETH-USD-PERP")
```

Refer to the WebSocket Channels documentation for a list of supported channels.