About
About ArbSonar
ArbSonar is a free scanner for cross-venue prediction market spreads. We built it because comparing Polymarket, Kalshi and Limitless by hand is slow, and most arbitrage screenshots leave out fees and order-book depth.
What we do
We read public market data from Polymarket, Kalshi and Limitless, match contracts that look like the same event, then price YES on one venue plus NO on the other. The number you see is after taker fees and capped by the size actually quoted on the book.
How we match
Venues word the same contract differently. We compare normalized words, dates, thresholds, times, direction (above or below), geography and negation. Each pair gets a confidence score. 90% and up is usually the same contract; lower scores deserve a closer read. The score is on every row, so you can judge it yourself.
What we don't do
We don't place orders, hold funds, or promise a risk-free return. Two markets can look identical and still resolve differently. Read both rule sets, check the depth, and treat every number as an estimate rather than a guarantee.
Corrections
If a pair is wrong or a fee is out of date, tell us. We would rather remove a bad match than defend it. The same goes for translations: if a Chinese or Korean phrase reads badly, we want to know.