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Markets WebSocket

The Markets WebSocket endpoint provides real-time market data including order book updates, price changes, and trade notifications.
Authentication RequiredThis WebSocket endpoint requires Ed25519 signature authentication in the connection handshake. See the Authentication guide for details.

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Endpoint

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

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Subscription Types

ValueDescription
SUBSCRIPTION_TYPE_MARKET_DATAFull order book and market stats
SUBSCRIPTION_TYPE_MARKET_DATA_LITELightweight price data only
SUBSCRIPTION_TYPE_TRADEReal-time trade notifications

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Market Data Subscription

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Subscribe to Full Market Data

{
  "subscribe": {
    "requestId": "md-sub-1",
    "subscriptionType": "SUBSCRIPTION_TYPE_MARKET_DATA",
    "marketSlugs": ["market-slug-1", "market-slug-2"]
  }
}

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Market Data Response

Full order book with market statistics: 
{
  "requestId": "md-sub-1",
  "subscriptionType": "SUBSCRIPTION_TYPE_MARKET_DATA",
  "marketData": {
    "marketSlug": "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": "MARKET_STATE_OPEN",
    "stats": {
      "lastTradePx": {"value": "0.55", "currency": "USD"},
      "sharesTraded": "150000",
      "openInterest": "500000",
      "highPx": {"value": "0.58", "currency": "USD"},
      "lowPx": {"value": "0.52", "currency": "USD"}
    },
    "transactTime": "2024-01-15T10:30:00Z"
  }
}

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Market Data Lite Subscription

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Subscribe to Lightweight Data

For reduced bandwidth, use the lite subscription: 
{
  "subscribe": {
    "requestId": "mdl-sub-1",
    "subscriptionType": "SUBSCRIPTION_TYPE_MARKET_DATA_LITE",
    "marketSlugs": ["market-slug-1"]
  }
}

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Market Data Lite Response

{
  "requestId": "mdl-sub-1",
  "subscriptionType": "SUBSCRIPTION_TYPE_MARKET_DATA_LITE",
  "marketDataLite": {
    "marketSlug": "market-slug-1",
    "currentPx": {"value": "0.55", "currency": "USD"},
    "lastTradePx": {"value": "0.55", "currency": "USD"},
    "bestBid": {"value": "0.54", "currency": "USD"},
    "bestAsk": {"value": "0.56", "currency": "USD"},
    "bidDepth": 5,
    "askDepth": 4,
    "sharesTraded": "150000",
    "openInterest": "500000"
  }
}

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Trade Subscription

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Subscribe to Trades

{
  "subscribe": {
    "requestId": "trade-sub-1",
    "subscriptionType": "SUBSCRIPTION_TYPE_TRADE",
    "marketSlugs": ["market-slug-1"]
  }
}

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Trade Response

{
  "requestId": "trade-sub-1",
  "subscriptionType": "SUBSCRIPTION_TYPE_TRADE",
  "trade": {
    "marketSlug": "market-slug-1",
    "price": {"value": "0.55", "currency": "USD"},
    "quantity": {"value": "100", "currency": "USD"},
    "tradeTime": "2024-01-15T10:30:00Z",
    "maker": {
      "side": "ORDER_SIDE_BUY",
      "intent": "ORDER_INTENT_BUY_LONG"
    },
    "taker": {
      "side": "ORDER_SIDE_SELL",
      "intent": "ORDER_INTENT_SELL_LONG"
    }
  }
}

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Market States

ValueDescription
MARKET_STATE_OPENMarket open for trading
MARKET_STATE_PREOPENMarket in pre-open phase
MARKET_STATE_SUSPENDEDTrading temporarily suspended
MARKET_STATE_HALTEDTrading halted
MARKET_STATE_EXPIREDMarket has expired
MARKET_STATE_TERMINATEDMarket terminated
MARKET_STATE_MATCH_AND_CLOSE_AUCTIONMarket in closing auction

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Order Side

ValueDescription
ORDER_SIDE_BUYBuy order
ORDER_SIDE_SELLSell order

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Order Intent

ValueDescription
ORDER_INTENT_BUY_LONGBuy YES shares
ORDER_INTENT_SELL_LONGSell YES shares
ORDER_INTENT_BUY_SHORTBuy NO shares
ORDER_INTENT_SELL_SHORTSell NO shares

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Debouncing

For high-frequency markets, enable response debouncing to reduce message volume: 
{
  "subscribe": {
    "requestId": "md-sub-1",
    "subscriptionType": "SUBSCRIPTION_TYPE_MARKET_DATA",
    "marketSlugs": ["market-slug-1"],
    "responsesDebounced": true
  }
}
When debouncing is enabled, updates are batched and sent at regular intervals rather than on every change.
Subscription LimitsYou can subscribe to a maximum of 100 markets per subscription. Use multiple subscriptions if you need more.

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Order Book Depth

The full market data subscription includes the top levels of the order book. Each level shows:
FieldDescription
pxPrice level
qtyTotal quantity at this price
Order book levels are sorted best-to-worst (highest bid first, lowest ask first).