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WebSocketFinance & Macro

Kalshi Exchange API (WebSocket + REST)

Kalshi Exchange API (WebSocket + REST) is a websocket from Kalshi providing finance & macro data. Kalshi is a CFTC-regulated event-contract exchange offering real-time market data and trade execution over REST, WebSocket, and FIX. It lists FOMC rate, CPI/inflation, jobs, GDP and recession markets, making it a cross-venue odds/price reference a Polymarket bot can use to arbitrage, hedge, or sanity-check implied probabilities against a regulated US exchange.

At a glance

ProviderKalshi
TypeWebSocket
CategoryFinance & Macro
Real-timeYes — streaming
AuthAPI key
PricingFree API access for verified users; per-trade transaction fees apply (no API subscription) — API access: free for all verified Kalshi accounts (no API subscription fee), Trading: per-contract transaction fee on expected earnings (varies by market); maker fees only charged on execution, Rate-limit tiers (Basic free → Advanced/Expert/Premier/Paragon/Prime/Prestige) earned by trading volume, not paid, No charge to cancel resting orders

What data it provides

  • Live bid/ask/last-trade ticker per market (FOMC, CPI, jobs, GDP, recession, plus politics/sports/econ)
  • Full order book: orderbook_snapshot + incremental orderbook_delta updates
  • Public trade feed (executed trades: price, size, timestamp)
  • Markets, events, and series metadata with resolution rules and settlement
  • Private user data: fills, positions, orders, order-group updates
  • Market lifecycle events (open/close/settle) via market_lifecycle_v2

Features

  • WebSocket (wss://external-api-ws.kalshi.com/trade-api/ws/v2) plus REST and FIX protocols; demo/sandbox environment available
  • Token-bucket rate limits (since 2026-04-23): separate Read/Write buckets, ~200 read/100 write tokens-per-sec on free Basic tier, up to thousands on higher tiers with 2x burst
  • Real-time push: snapshot + delta order book, ticker, and trade channels
  • RSA-PSS signed-header auth (KALSHI-ACCESS-KEY/SIGNATURE/TIMESTAMP) for both REST and WS
  • Covers macro/Fed/CPI event contracts that directly mirror Polymarket FOMC/CPI/recession markets
  • Community SDKs in Python, Rust, and others; demo env for testing

Links

Use it in a bot

Other finance & macro data sources

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 resources directory or the strategy database.
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