WebSocket API

The Paradex WebSocket API provides real-time market data and account updates. WebSockets allow for a persistent connection between the client and server, enabling efficient two-way communication.

Server URLs

Public vs Private Channels

The Paradex WebSocket API provides two types of channels:

• Public Channels: Publish information about the exchange that is not specific to a particular account. Examples include market summary, order book, trades, etc. You do not need to authenticate to subscribe to public channels.

• Private Channels: Publish information about a particular account. You need to authenticate to subscribe to private channels.

Establishing a Connection

To establish a WebSocket connection, you can use various programming languages and libraries. When running Python-based code, Python 3.10+ is recommended.

Example in Python

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import websocket
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import json
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websocket_url = "wss://ws.api.testnet.paradex.trade/v1"
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# Define a callback to check connection success
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def on_open(ws):
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    print('Connected')
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# Connect to the WebSocket server
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ws = websocket.WebSocketApp(websocket_url, on_open=on_open)
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# Wait for a response
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ws.run_forever()

Upon successful connection, you should see:

Connected

Maintaining a Connection

Paradex has implemented ping/pong functionality as part of the WebSocket specification. This works at the protocol level:

• The server sends a ping message every 55 seconds
• The client must respond with a pong within 5 seconds
• Upon receiving the pong, the connection is renewed for 60 seconds
• If the server doesn’t receive a pong within the 5-second window, the connection is terminated

Most modern WebSocket libraries and frameworks automatically handle ping/pong messages. If you’re using older libraries or building a WebSocket client from scratch, you may need to implement this functionality manually.

To display incoming ping messages, you can use the following wscat command:

$
wscat -P -w 120 -c wss://ws.api.testnet.paradex.trade/v1 -x '{"id":1,"jsonrpc":"2.0","method":"subscribe","params":{"channel":"markets_summary"}}' | grep "ping"

Next Steps

• Learn how to authenticate your WebSocket connection
• Explore available channels and subscription methods
• Understand error handling for WebSocket connections