Is there a Kalshi data API?
By Faizan Ahmad. Updated .
Yes: Kalshi and Polymarket each run their own public APIs for their raw markets, and the Tradytics prediction market data API serves both in one key, with an archive of 5.95 million Kalshi and Polymarket markets and 41.4 million trades back to June 2021, settled ones included, the chance of each outcome on every live finance question, and options flow, dark pool and dealer data beside it. It is part of Pro, at 300 calls a minute and 50,000 a day.
What the archive holds
| Venue | Markets | Trades | History |
|---|---|---|---|
| Kalshi | 5,748,581 | 30.2 million | Since June 30, 2021, settled ones included |
| Polymarket | 202,780 | 11.2 million | Settled ones included |
| Both | 5.95 million | 41.4 million | Back to June 2021 |
Settled markets keep their outcome, so a question from 2022 reads the same as one that opened this morning.
What Tradytics adds to the venues' own APIs
- Two venues, one shape. Kalshi and Polymarket questions come back in the same fields, so an index close, a Fed decision or an earnings beat reads the same whichever venue lists it.
- The settled archive. Every market back to June 2021 with how it came out, ready for a study or a backtest.
- Chances per outcome. Each live finance question comes with the chance of every outcome and where it is likely to land, the same numbers Tradytics Probabilities charts.
- One key for the rest. The same Pro key serves options flow (every session since March 31, 2025, 19.96 million orders), dark pool prints ranked against each stock's last 12 months, dealer gamma, delta, vanna and charm, Signals and AI Fund trades.
What people build with it
- The chance of a Fed cut on one chart with QQQ's net options flow.
- An earnings-beat question beside the stock's flow and its past report-day moves.
- S&P 500 close chances next to same-day SPX options. Tradytics' own study of the archive found the two price the close the same way.
- A backtest such as "hold SMH when Kalshi's Fed market favors a cut, QQQ otherwise", which runs as written in the Tradytics backtester.
Plan and limits
| Free | Plus | Pro | |
|---|---|---|---|
| Probabilities in the app | S&P 500 and Nasdaq | Every stock and report | Every stock and report |
| API | 300 calls a minute, 50,000 a day | ||
| Price | $0 | $39 a month | $69 a month or $499 a year |
The base URL is https://tradytics.com/api/public/v1. Endpoints, fields and a sample response are in the prediction market data API page and the API docs.
Common questions
Does Kalshi have a public API?
Yes, for its own markets. Tradytics serves Kalshi and Polymarket together, with settled history back to June 2021 and the chance of each outcome.
Can I get settled Kalshi market history?
Yes. The Tradytics archive holds 5,748,581 Kalshi markets since June 30, 2021, settled ones included, with 30.2 million trades.
Does it include Polymarket?
Yes. 202,780 Polymarket markets with 11.2 million trades sit in the same archive and the same response shape.
Which plan includes the API?
Pro, $69 a month or $499 a year: 300 calls a minute and 50,000 a day across prediction markets, options flow, dark pool and the rest.