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

# Markets WebSocket

> Real-time market data, order book, and trades

# Markets WebSocket

The Markets WebSocket endpoint provides real-time market data including order book updates, price changes, and trade notifications.

## Endpoint

```
wss://api.polymarket.us/v1/ws/markets
```

## Subscription Types

| Value | Type               | Description                      |
| ----- | ------------------ | -------------------------------- |
| 1     | MARKET\_DATA       | Full order book and market stats |
| 2     | MARKET\_DATA\_LITE | Lightweight price data only      |
| 3     | TRADE              | Real-time trade notifications    |

## Market Data Subscription

### Subscribe to Full Market Data

```json theme={null}
{
  "subscribe": {
    "request_id": "md-sub-1",
    "subscription_type": 1,
    "market_slugs": ["market-slug-1", "market-slug-2"]
  }
}
```

### Market Data Response

Full order book with market statistics:

```json theme={null}
{
  "request_id": "md-sub-1",
  "subscription_type": 1,
  "market_data": {
    "market_slug": "market-slug-1",
    "bids": [
      {"px": {"value": "0.54", "currency": "USD"}, "qty": "1000"},
      {"px": {"value": "0.53", "currency": "USD"}, "qty": "2500"}
    ],
    "offers": [
      {"px": {"value": "0.56", "currency": "USD"}, "qty": "800"},
      {"px": {"value": "0.57", "currency": "USD"}, "qty": "1500"}
    ],
    "state": 1,
    "stats": {
      "last_trade_px": {"value": "0.55", "currency": "USD"},
      "shares_traded": "150000",
      "open_interest": "500000",
      "high_px": {"value": "0.58", "currency": "USD"},
      "low_px": {"value": "0.52", "currency": "USD"}
    },
    "transact_time": "2024-01-15T10:30:00Z"
  }
}
```

## Market Data Lite Subscription

### Subscribe to Lightweight Data

For reduced bandwidth, use the lite subscription:

```json theme={null}
{
  "subscribe": {
    "request_id": "mdl-sub-1",
    "subscription_type": 2,
    "market_slugs": ["market-slug-1"]
  }
}
```

### Market Data Lite Response

```json theme={null}
{
  "request_id": "mdl-sub-1",
  "subscription_type": 2,
  "market_data_lite": {
    "market_slug": "market-slug-1",
    "current_px": {"value": "0.55", "currency": "USD"},
    "last_trade_px": {"value": "0.55", "currency": "USD"},
    "best_bid": {"value": "0.54", "currency": "USD"},
    "best_ask": {"value": "0.56", "currency": "USD"},
    "bid_depth": 5,
    "ask_depth": 4,
    "shares_traded": "150000",
    "open_interest": "500000"
  }
}
```

## Trade Subscription

### Subscribe to Trades

```json theme={null}
{
  "subscribe": {
    "request_id": "trade-sub-1",
    "subscription_type": 3,
    "market_slugs": ["market-slug-1"]
  }
}
```

### Trade Response

```json theme={null}
{
  "request_id": "trade-sub-1",
  "subscription_type": 3,
  "trade": {
    "market_slug": "market-slug-1",
    "price": {"value": "0.55", "currency": "USD"},
    "quantity": {"value": "100", "currency": "USD"},
    "trade_time": "2024-01-15T10:30:00Z",
    "maker": {
      "side": 1,
      "intent": 1
    },
    "taker": {
      "side": 2,
      "intent": 2
    }
  }
}
```

## Market States

| Value | State      | Description                   |
| ----- | ---------- | ----------------------------- |
| 1     | OPEN       | Market open for trading       |
| 2     | PREOPEN    | Market in pre-open phase      |
| 3     | SUSPENDED  | Trading temporarily suspended |
| 4     | HALTED     | Trading halted                |
| 5     | EXPIRED    | Market has expired            |
| 6     | TERMINATED | Market terminated             |

## Debouncing

For high-frequency markets, enable response debouncing to reduce message volume:

```json theme={null}
{
  "subscribe": {
    "request_id": "md-sub-1",
    "subscription_type": 1,
    "market_slugs": ["market-slug-1"],
    "responses_debounced": true
  }
}
```

When debouncing is enabled, updates are batched and sent at regular intervals rather than on every change.

<Tip>
  **Subscription Limits**

  You can subscribe to a maximum of 100 markets per subscription. Use multiple subscriptions if you need more.
</Tip>

## Order Book Depth

The full market data subscription includes the top levels of the order book. Each level shows:

| Field | Description                  |
| ----- | ---------------------------- |
| `px`  | Price level                  |
| `qty` | Total quantity at this price |

Order book levels are sorted best-to-worst (highest bid first, lowest ask first).