Quick answer
The Kairos API is a REST and WebSocket surface for prediction markets: market data, order execution, portfolio analytics, sports markets, and trader intelligence, aggregated across Kalshi, Polymarket, Predict.fun, and Hyperliquid. Data lives at data.kairos.trade, execution at execution.kairos.trade, and streaming at stream.kairos.trade.
Base URLs
| Service | URL | What it serves |
|---|---|---|
| Data API | https://data.kairos.trade | Markets, candles, trades, search, PnL, sports, trader stats |
| Order Execution | https://execution.kairos.trade | Submit, cancel, and query orders (REST and WebSocket) |
| Market Data Stream | wss://stream.kairos.trade | Real-time market data WebSocket (protobuf) |
| Order Execution Stream | wss://execution.kairos.trade/ws | Real-time order and status updates (JSON) |
Two data APIs
The separate Market Data API (md.kairos.trade) is a lighter-weight, read-only beta service with a free anonymous tier and ETag caching. Reach for it instead of the Data API when you only need candles, trades, or marks at scale. It needs no signup.
Providers
The API aggregates multiple prediction market venues. Pass the numeric provider_id, or the string provider name such as "predictfun", wherever an endpoint takes a provider.
| Provider | ID | Description |
|---|---|---|
| Kalshi | 1 | US-regulated prediction market (CFTC designated contract market) |
| Polymarket | 2 | Blockchain-based prediction market on Polygon |
| Opinion | 3 | Decentralized prediction market. Sunset, no longer active. |
| Predict.fun | 8 | Blockchain-based prediction market on BNB Chain |
| Hyperliquid | 9 | HIP-4 outcome markets on the Hyperliquid L1 |
Modules
- Markets (/markets): market details, prices, metadata, and sibling outcomes
- Discovery (/api/markets/discover/v2): discover, trending, breaking, and expiring markets
- Crypto markets (/markets/crypto): short-interval crypto up-or-down contracts and oracle prices
- Candles and trades (/candles, /trades): OHLCV history and prints, single or batched up to 200 contracts
- Search (/search): market and event search with suggestions
- PnL and trader stats (/pnl, trader analytics): portfolio and trader intelligence
- Orders (execution.kairos.trade): submission, cancellation, and status
The interactive reference with a live tester for every endpoint, 102 in total, plus the machine-readable OpenAPI specs, lives at app.kairos.trade/docs. Everything on the Market Data API and every endpoint marked free works without a signup. Authentication for the rest is covered in Authentication.