> ## Documentation Index
> Fetch the complete documentation index at: https://docs.delphimarkets.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Kalshi WebSocket

> Real-time price, orderbook, and trade streaming for Kalshi markets

## Connection

Connect to the Kalshi WebSocket endpoint:

```
wss://api.delphiterminal.co/ws/kalshi
```

No authentication is required for WebSocket connections.

| Property         | Value                   |
| ---------------- | ----------------------- |
| Protocol         | WebSocket (wss\://)     |
| Keepalive        | Ping every 54 seconds   |
| Timeout          | 60 seconds without pong |
| Max Message Size | 512 KB                  |

## Subscribing to markets

Once connected, send a JSON message to subscribe using `klsi_id`:

```json theme={"theme":"one-dark-pro"}
{
  "action": "subscribe",
  "klsi_ids": ["KXBTCD-25FEB14-B55000", "KXETHD-25FEB14-B3100"],
  "message_types": ["prices", "orderbook", "trades"]
}
```

| Field           | Type   | Required | Description                                                                                                  |
| --------------- | ------ | -------- | ------------------------------------------------------------------------------------------------------------ |
| `action`        | string | Yes      | `subscribe` or `unsubscribe`                                                                                 |
| `klsi_ids`      | array  | Yes      | Array of Kalshi market identifiers                                                                           |
| `message_types` | array  | No       | `["prices"]`, `["orderbook"]`, `["trades"]`, or any combination. Defaults to prices and orderbook if omitted |

## Unsubscribing

```json theme={"theme":"one-dark-pro"}
{
  "action": "unsubscribe",
  "klsi_ids": ["KXBTCD-25FEB14-B55000"]
}
```

## Message types

### Price messages

Real-time price updates for subscribed markets:

```json theme={"theme":"one-dark-pro"}
{
  "klsi_id": "KXBTCD-25FEB14-B55000",
  "price": 0.65,
  "yes_bid": 0.64,
  "yes_ask": 0.66,
  "volume": 15000,
  "open_interest": 8500,
  "last_update": "2026-02-03T14:30:00Z"
}
```

### Orderbook messages

Real-time orderbook snapshots for subscribed markets:

```json theme={"theme":"one-dark-pro"}
{
  "klsi_id": "KXBTCD-25FEB14-B55000",
  "bid_side": [0, 0, 0, "...", 150, 200, 100],
  "ask_side": [100, 150, 200, "...", 0, 0, 0],
  "last_update": "2026-02-03T14:30:00Z"
}
```

### Trade messages

Real-time trade executions for subscribed markets:

```json theme={"theme":"one-dark-pro"}
{
  "id": "trade123",
  "klsi_id": "KXBTCD-25FEB14-B55000",
  "exchange": "klsi",
  "yes_price": 0.65,
  "no_price": 0.35,
  "count": 10,
  "taker_side": "buy",
  "last_update": "2026-02-03T14:30:00Z"
}
```

## Full example

```javascript theme={"theme":"one-dark-pro"}
const ws = new WebSocket("wss://api.delphiterminal.co/ws/kalshi");

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

  ws.send(JSON.stringify({
    action: "subscribe",
    klsi_ids: ["KXBTCD-25FEB14-B55000"],
    message_types: ["prices", "orderbook", "trades"]
  }));
};

ws.onmessage = (event) => {
  const data = JSON.parse(event.data);
  console.log("Received:", data);
};

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

## Important notes

* **No authentication required** for WebSocket connections
* Use `klsi_id` (Kalshi 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)