Polygon.io WebSocket Pricing Across Multi-Asset Feeds

Building cross-market trading setups often runs into a wall when pricing individual data feeds across asset categories. Evaluating Polygon.io WebSocket pricing shows how quickly running multiple socket streams for stocks, forex, and crypto adds up on a monthly bill. By the end of this guide, you will see how cross-asset pricing stacks up and how to pull live crypto and forex data over a single socket connection without separate fees.

TL;DR: Polygon separates subscriptions by asset class, meaning multi-strategy bots quickly require hundreds of dollars each month. A unified multi-asset feed from RealMarketAPI lets you stream crypto, forex, gold, and stocks under a single subscription starting at $14.99 per month for 10 concurrent connections.

How per-asset subscription models inflate streaming bills

Many market data providers split their infrastructure into independent silos: equities, foreign exchange, and digital assets. When you start an algorithmic trading project focusing on a single equity index or one currency pair, this isolation feels fine. The basic plan covers your target ticker, and latency remains predictable.

Friction begins when your strategies cross markets. A statistical arbitrage strategy might monitor BTCUSD alongside the S&P 500 (US500) and gold (XAUUSD) to track safe-haven capital flows. If your data provider charges for real-time WebSocket feeds per asset silo, you cannot simply listen to another symbol. You must buy into an additional subscription tier for every market type your code monitors.

Stacking these products introduces several operational pains:

1. Multiple API keys and connection lifecycles across distinct server hosts.
2. Compounding monthly costs where each asset group adds its own minimum spend.
3. Disjointed message formats requiring different parsing adapters for each market.

Breaking down Polygon.io WebSocket pricing across asset silos

To get real-time WebSocket data on Polygon.io, you must purchase a paid plan within each asset category. Real-time US stocks require a paid Stocks plan. If you also want live forex pairs like EURUSD or GBPUSD, you need an active Currencies/Forex tier. Adding crypto like BTCUSD or ETHUSD requires its own separate plan.

When you sum these subscriptions for a multi-asset setup, your monthly data budget quickly crosses $100 to $200 per month just to receive streaming ticks. If you want historical depth or institutional-grade feeds across all three classes, the monthly total climbs even higher.

For a small fund or an independent developer building automated systems, paying three distinct platform fees creates unnecessary overhead. Managing three separate socket connections also complicates worker reconnection logic and increases memory footprint across container instances.

Connecting to a single multi-asset WebSocket feed

Instead of opening distinct sockets for equities, currencies, and cryptocurrencies, a unified gateway serves all symbols over one protocol. RealMarketAPI exposes over 60 symbols covering gold (XAUUSD), silver (XAGUSD), forex (EURUSD, USDJPY), crypto (BTCUSD, ETHUSD), stocks (AAPL), and commodities (USOIL) under one key.

Before opening a persistent streaming connection, you can inspect the current market state using standard REST endpoints. Authentication uses a standard apiKey query parameter.

Here is how to test live pricing for XAUUSD via curl:

curl "https://api.realmarketapi.com/api/v1/price?apiKey=YOUR_API_KEY&symbolCode=XAUUSD&timeFrame=M1"

The server returns a JSON payload containing bid, ask, volume, and candle boundaries:

{
  "SymbolCode": "XAUUSD",
  "OpenPrice": 2350.10,
  "ClosePrice": 2352.40,
  "HighPrice": 2353.00,
  "LowPrice": 2349.80,
  "Bid": 2352.35,
  "Ask": 2352.45,
  "Volume": 1420,
  "OpenTime": "2025-05-10T12:00:00Z"
}

(Values illustrative)

Notice that the schema is identical whether you request XAUUSD, BTCUSD, or EURUSD. This consistency prevents writing bespoke normalization logic for every upstream provider.

Streaming BTCUSD and EURUSD over one connection

With multi-asset support built into the base socket at wss://api.realmarketapi.com, you can receive pricing events for disparate asset classes without running separate client processes. For teams implementing cheap WebSocket market data, this consolidation reduces network complexity.

The following Python script uses asyncio and websockets to authenticate and listen for ticks across both crypto and forex pairs:

import asyncio
import json
import websockets

API_KEY = "YOUR_API_KEY"
WS_URL = f"wss://api.realmarketapi.com?apiKey={API_KEY}"

async def stream_market_data():
    async with websockets.connect(WS_URL) as ws:
        # Subscribe to crypto and forex on the same socket
        subscribe_message = {
            "action": "subscribe",
            "symbols": ["BTCUSD", "EURUSD", "XAUUSD"],
            "timeFrame": "M1"
        }
        await ws.send(json.dumps(subscribe_message))
        print("Subscribed to BTCUSD, EURUSD, and XAUUSD")

        while True:
            message = await ws.recv()
            data = json.loads(message)
            symbol = data.get("SymbolCode")
            bid = data.get("Bid")
            ask = data.get("Ask")
            print(f"[{symbol}] Bid: {bid} | Ask: {ask}")

if __name__ == "__main__":
    asyncio.run(stream_market_data())

By multiplexing symbols into a single socket session, your local event loop handles fewer file descriptors and maintains lower idle network usage compared to running three discrete clients.

Comparing tier limits from 10 to 100 concurrent sockets

While combining streams saves money, production architectures must account for plan limits and concurrency caps. In many multi-asset strategies, running one socket is insufficient. You may want isolated worker processes for execution, risk checking, and portfolio tracking.

Here is how RealMarketAPI structures its paid tiers:

• Free ($0/month): 5,000 requests per month covering gold, silver, BTC, ETH, EURUSD, and Google on M1, M5, and H1 timeframes. REST only, no credit card required. Suitable for backtesting toy scripts, but no WebSocket access.
• Starter ($4.99/month): 20,000 requests per month across all 60+ symbols and all timeframes with 30 days of history. Gives access to the Volatility API, but streaming remains REST-focused.
• Plus ($14.99/month): 75,000 monthly requests, 3 months of history, and access to the WebSocket gateway with 10 concurrent connections.
• Pro ($34.99/month): 200,000 monthly requests, 1 year of history, 100 concurrent WebSocket connections, the Intelligence API, and access to the 33-tool Model Context Protocol (MCP) server at https://ai.realmarketapi.com/mcp.
• Business ($74.99/month): 1,000,000 requests, up to 10 years of history, and 300 concurrent WebSocket connections.

Annual billing saves up to 15% across these paid plans.

Choosing a tier based on bot architecture and connection counts

Deciding between the Plus ($14.99) and Pro ($34.99) tiers depends on your execution model. If you run an algorithmic bot vs AI agent architecture, you might deploy separate containers: one container for order routing, another for risk guardrails, and another for analytics.

With the Plus tier, you have 10 concurrent sockets. That is enough for a microservice deployment with a primary worker, a backup hot-standby, and local testing scripts. However, if your architecture spins up dynamic worker threads for each individual symbol or runs distributed backtests requiring concurrent streaming feeds, the 10-connection limit will throttle your nodes. In that scenario, moving to Pro gives you 100 concurrent connections alongside the MCP server for AI agent workflows.

Keep in mind that while a multi-asset gateway provides broader breadth at a lower cost, dedicated single-market institutional feeds may offer deeper order books for niche equities. For developers building systems that react to broad market swings across crypto, gold, and currencies, unified pricing eliminates the subscription bloat common to older data brokers.

Grab a free key at RealMarketAPI, run the curl check above for BTCUSD or XAUUSD, and see the response format before configuring your WebSocket listeners.