About LineGap

What this is. Kalshi and Polymarket both list moneyline-style markets on the same games, and the two crowds rarely agree on the price. LineGap indexes both venues' public markets, matches games deterministically (same teams, same date, same market type), and shows each matched game's two prices, the gap between them, and how that gap moved over time. Data refreshes about every five minutes.

Where the data comes from. The venues' own public APIs, via our own index. Prices shown are listed prices at index time — real executable prices, spreads, and fees differ, and anything here can be stale by the time you look at it. When sharp-sportsbook consensus data is available, game pages also show a de-vigged fair probability next to the contract price.

What this is not. LineGap sells nothing, holds no funds, executes no trades, and recommends no positions. It is not affiliated with Kalshi, Polymarket, or any sportsbook. Pages are identical for every visitor — impersonal market analytics, not advice. If you want to be notified when a gap opens rather than watching a page, that's what our sibling tool Polykal does.

Want the math? The methodology behind these numbers — what +EV means on an event contract, how Kalshi's fee formula changes your breakeven, why the two venues disagree, and how to de-vig a sportsbook line by hand — is written up in these guides. They're free to read and assume no prior knowledge.