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WebSocketStocks & Equities

Polygon.io (Massive) Stocks WebSocket

Polygon.io (Massive) Stocks WebSocket is a websocket from Polygon.io / Massive providing stocks & equities data. Push WebSocket stream of real-time US-equity market data — tick trades, NBBO quotes, and per-second/per-minute OHLC aggregates across all 19 US exchanges, dark pools and OTC. A Polymarket bot can subscribe to TSLA/SPX-component prints and instantly evaluate whether the underlying is above a strike for "will close above $X" markets. Note: Polygon.io rebranded to Massive in late 2025; polygon.io 301-redirects to massive.com.

At a glance

ProviderPolygon.io / Massive
TypeWebSocket
CategoryStocks & Equities
Real-timeYes — streaming
AuthAPI key
PricingFree tier (delayed/EOD); real-time WebSocket from $79/mo (IEX) or $199/mo (full SIP) — Basic: Free — end-of-day/15-min delayed, 5 API calls/min, no production WebSocket, Starter: $29/mo — 15-min delayed data, unlimited calls, delayed WebSocket, 5yr history, Developer: $79/mo — real-time IEX feed over WebSocket, unlimited calls, 10yr history, Advanced: $199/mo — full real-time SIP (all exchanges) WebSocket, 20+yr history

What data it provides

  • Tick-level trades for all US equity tickers
  • NBBO quotes (national best bid/offer)
  • Per-second aggregated OHLC + volume bars
  • Per-minute aggregated OHLC + volume bars
  • Fair Market Value (FMV) real-time stream
  • LULD halt and Net Order Imbalance (NOI) events

Features

  • Real-time push: subscribe to T.*, Q.*, A.* (sec), AM.* (min) channels
  • Coverage: 19 US exchanges + dark pools, FINRA TRFs, and OTC (100% market)
  • Full SIP real-time requires Advanced ($199/mo); cheaper Developer tier streams IEX-only
  • 20+ years of historical data available via REST/flat files to backfill
  • Unlimited API calls on all paid plans; official Python/Go/JS/Kotlin client SDKs
  • Single persistent WebSocket connection with API-key auth message

Links

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Listed, not endorsed. Pricing and capabilities change without notice — check the provider's own documentation before you depend on anything here. Browse the full data feeds directory or the strategy database.
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