Guides
Questions about prediction markets, answered from the live board rather than from memory. Every number on these pages is recomputed with the engine, so they change as the markets do.
Is there arbitrage between Kalshi and Polymarket?
The live answer, with every gap shown before and after fees.
Kalshi vs Polymarket: how the two venues actually differ
Market counts, volume, fees and overlap, counted from today's board.
How accurate are prediction market prices?
Our own resolved markets, bucketed by price against what actually happened.
How much do Kalshi and Polymarket fees actually cost?
Measured per contract on the live board, and why the cost peaks near 50c.
Do Kalshi and Polymarket odds agree?
Yes, closely — the median gap is half a point. The widest gaps, and what causes each.
By league
Live prices from both venues, one page per league, kept at the same address whether or not the season is running: NFL · College football · MLB · WNBA · MLS · Premier League · La Liga · EFL · Champions & Europa · Counter-Strike 2 · League of Legends · Dota 2 · Valorant · Tennis · UFC.
Reference
Prediction market glossary — spread, edge after fees, settlement risk and the Kalshi fee formula, defined the way a cross-venue engine has to define them. Everything on this site in one plain-text file: llms-full.txt. The open JSON endpoints, documented: /data. Price moves as a feed: Atom · JSON.