Realtime BBO

# Python (websocket-client)
# pip install websocket-client
import json
import websocket

def on_open(ws):
    sub = {
        "type": "subscribe",
        "channels": ["bbo"],
        "symbols": ["SP500-USD"]  # or ["*"]
    }
    ws.send(json.dumps(sub))

def on_message(ws, message):
    data = json.loads(message)
    print("BBO update:", json.dumps(data, indent=2))

def on_error(ws, error):
    print("Error:", error)

def on_close(ws, close_status_code, close_msg):
    print("Closed:", close_status_code, close_msg)

if __name__ == "__main__":
    ws = websocket.WebSocketApp(
        "wss://mds.qfex.com",
        on_open=on_open,
        on_message=on_message,
        on_error=on_error,
        on_close=on_close,
    )
    ws.run_forever()