Market Price Updates

Receive real-time price updates for individual price types (mark, last, index, mid) as they change.

Endpoint

Public subscriptions (candles, marketPrices, orderbook):

wss://papi.synthetix.io/v1/ws/info

Private subscriptions (subAccountUpdates - requires authentication):

wss://papi.synthetix.io/v1/ws/trade

Overview

The marketPrices subscription provides real-time updates for individual price types as they are published. Each price type (mark, last, index, mid) is sent as a separate update message when it changes.

Important: Unlike the REST API which returns all price types in a single response, the WebSocket sends individual updates for each price type separately.

Subscription Request

Subscribe to Market Price Updates

{
  "id": "sub-1",
  "method": "subscribe",
  "params": {
    "type": "marketPrices",
    "symbol": "BTC-USDT"
  }
}

Subscribe to All Markets

{
  "id": "sub-all",
  "method": "subscribe",
  "params": {
    "type": "marketPrices",
    "symbol": "ALL"
  }
}

Alternatively, omit the symbol parameter to subscribe to all markets (defaults to "ALL"):

{
  "id": "sub-all",
  "method": "subscribe",
  "params": {
    "type": "marketPrices"
  }
}

Request Parameters

Price Update Messages

Update Message Format

{
  "method": "market_price_update",
  "data": {
    "symbol": "BTC-USDT",
    "price": "50125.50",
    "lastUpdateTime": "2025-01-03T12:34:56.789Z",
    "updateType": "mark"
  }
}

Message Fields

Price Types

Each price type is sent as a separate update:

Update Examples

Mark Price Update

{
  "method": "market_price_update",
  "data": {
    "symbol": "BTC-USDT",
    "price": "50125.50",
    "lastUpdateTime": "2025-01-03T12:34:56.789Z",
    "updateType": "mark"
  }
}

Index Price Update

{
  "method": "market_price_update",
  "data": {
    "symbol": "ETH-USDT",
    "price": "3250.75",
    "lastUpdateTime": "2025-01-03T12:34:57.123Z",
    "updateType": "index"
  }
}

Last Price Update

{
  "method": "market_price_update",
  "data": {
    "symbol": "SOL-USDT",
    "price": "125.48",
    "lastUpdateTime": "2025-01-03T12:34:57.456Z",
    "updateType": "last"
  }
}

Mid Price Update

{
  "method": "market_price_update",
  "data": {
    "symbol": "BTC-USDT",
    "price": "50124.25",
    "lastUpdateTime": "2025-01-03T12:34:58.789Z",
    "updateType": "mid"
  }
}

Implementation Example

const ws = new WebSocket('wss://papi.synthetix.io/v1/ws/info');
 
ws.onopen = () => {
  ws.send(JSON.stringify({
    id: 'sub-1',
    method: 'subscribe',
    params: {
      type: 'marketPrices',
      symbol: 'BTC-USDT'
    }
  }));
};
 
// Cache prices by type
const priceCache = new Map();
 
ws.onmessage = (event) => {
  const message = JSON.parse(event.data);
 
  if (message.method === 'market_price_update') {
    const { symbol, price, updateType } = message.data;
 
    if (!priceCache.has(symbol)) {
      priceCache.set(symbol, {});
    }
    priceCache.get(symbol)[updateType] = price;
 
    console.log(`${symbol} ${updateType}: ${price}`);
  }
};

Subscribe to All Markets

ws.send(JSON.stringify({
  id: 'sub-all',
  method: 'subscribe',
  params: {
    type: 'marketPrices',
    symbol: 'ALL'
  }
}));

Use Cases

Trading Interfaces

• Price Tickers: Display real-time mark, last, and index prices
• Price Type Comparison: Compare different price types for arbitrage
• Latency Monitoring: Track price update frequency and freshness

Risk Management

• Mark Price Monitoring: Track mark prices for margin calculations
• Price Divergence: Monitor differences between price types
• Price Staleness: Alert on outdated prices using lastUpdateTime

Market Analysis

• Price Discovery: Analyze how different price types move
• Spread Analysis: Calculate spreads between mark and index
• Update Frequency: Monitor how often each price type updates

Implementation Notes

• Update Frequency: Each price type updates independently when it changes
• Separate Messages: You receive one message per price type, not a combined message
• Timestamp Format: lastUpdateTime is in RFC3339 format
• Price Caching: Maintain a local cache to have the latest price for each type
• Memory Management: Clean up old price data to prevent memory leaks

Comparison: WebSocket vs REST API

Note: For comprehensive market data including funding rates, volume, and open interest, use the REST API endpoint Get Market Prices.

Error Handling

Subscription Errors

{
  "id": "sub-1",
  "status": 400,
  "result": null,
  "error": {
    "code": 400,
    "message": "Invalid symbol: XYZ-USDT not supported"
  }
}

Common Issues

Related Endpoints

• Get Market Prices - Comprehensive market data via REST API (all price types, funding, volume, OI)
• Get Markets - Available trading pairs
• Orderbook Updates - Real-time orderbook depth updates
• Candle Updates - OHLCV candlestick data