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Connection

Connect to the Predict.fun WebSocket endpoint: 
wss://api.delphiterminal.co/ws/pfun
No authentication is required for WebSocket connections.
PropertyValue
ProtocolWebSocket (wss://)
KeepalivePing every 54 seconds
Timeout60 seconds without pong
Max Message Size16 KB

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Subscribing to markets

Once connected, send a JSON message to subscribe using market_id: 
{
  "action": "subscribe",
  "market_ids": ["market123", "market456"],
  "message_types": ["prices", "orderbook", "trades"]
}
FieldTypeRequiredDescription
actionstringYessubscribe or unsubscribe
market_idsarrayYesArray of Predict.fun market identifiers
message_typesarrayNo["prices"], ["orderbook"], ["trades"], or any combination. Defaults to prices and orderbook if omitted

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Unsubscribing

{
  "action": "unsubscribe",
  "market_ids": ["market123"]
}

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Message types

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Price messages

{
  "type": "prices",
  "data": {
    "exchange": "pfun",
    "market_id": "market123",
    "price": 0.65,
    "yes_bid": 0.64,
    "yes_ask": 0.66,
    "last_update": "2026-02-06T12:00:00Z"
  }
}

​
Orderbook messages

{
  "type": "orderbook",
  "data": {
    "exchange": "pfun",
    "market_id": "market123",
    "venue_market_id": "venue123",
    "best_yes_price": 65,
    "best_yes_size": 100,
    "best_no_price": 35,
    "best_no_size": 50,
    "yes_side": [100, 200, 300],
    "no_side": [50, 100, 150],
    "server_time": "2026-02-06T12:00:00Z"
  }
}

​
Trade messages

{
  "type": "trades",
  "data": {
    "exchange": "pfun",
    "market_id": "market123",
    "yes_price": 0.65,
    "no_price": 0.35,
    "count": 10,
    "taker_side": "buy",
    "last_update": "2026-02-06T12:00:00Z"
  }
}

​
Full example

const ws = new WebSocket("wss://api.delphiterminal.co/ws/pfun");

ws.onopen = () => {
  console.log("Connected to Predict.fun WebSocket");

  ws.send(JSON.stringify({
    action: "subscribe",
    market_ids: ["market123"],
    message_types: ["prices", "orderbook", "trades"]
  }));
};

ws.onmessage = (event) => {
  const data = JSON.parse(event.data);

  if (data.type === "prices") {
    console.log("Price update:", data.data);
  } else if (data.type === "orderbook") {
    console.log("Orderbook update:", data.data);
  } else if (data.type === "trades") {
    console.log("Trade:", data.data);
  }
};

ws.onclose = () => console.log("Disconnected");
ws.onerror = (error) => console.error("WebSocket error:", error);

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Important notes

  • No authentication required for WebSocket connections
  • Use market_id (Predict.fun market identifier) to subscribe
  • Messages are only sent for markets you have explicitly subscribed to
  • Multiple markets can be subscribed in a single message
  • Trades must be explicitly requested (not included in the default subscription)