The PredictIt API: what it returns and what you may do with it
PredictIt publishes its market data free at https://www.predictit.org/api/marketdata/all/, with no API key. The data refreshes every 60 seconds. Only for non-commercial use, and you must credit PredictIt as the source.
The endpoints
PredictIt publishes its market data free at https://www.predictit.org/api/marketdata/all/, with no API key.
One market at a time: https://www.predictit.org/api/marketdata/markets/[ID].
The latest trade price and the best offers to buy and sell shares are available for any active market via an API.
What comes back
When we read it, the feed came back as XML and held 201 markets and 619 contracts.
Each contract carries: id, dateend, image, name, shortname, status, lasttradeprice, bestbuyyescost, bestbuynocost, bestsellyescost, bestsellnocost, lastcloseprice, displayorder.
The data refreshes every 60 seconds.
Data is updated every sixty seconds.
What you may do with it
Only for non-commercial use, and you must credit PredictIt as the source.
This data is for non-commercial use and PredictIt shall be attributed as the source.
No. PredictIt’s site terms ban automated trading; the API is read-only market data.
Use any manual or automated software, devices or other processes to engage in automated trading, to scrape or extract data from the Website
The other venues
Kalshi and Polymarket both run full trading APIs; see the Kalshi API and the Polymarket API.
