Polygon
Polygon (Polygon.io, rebranded as Massive in early 2026) provides real-time and historical market data APIs across US stocks, options, indices, forex, cryptocurrencies, and futures. Coverage is delivered through REST endpoints and WebSocket streams under a single api.polygon.io surface plus an S3 fl
2 channels
across 1 AsyncAPI spec
· Provider profile
Channels
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Client-to-server control messages (auth, subscribe, unsubscribe).Polygon WebSocket Streaming API
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Server-to-client market data events.Polygon WebSocket Streaming API