Live on Kalshi & Polymarket · updated continuously

Kalshi says 30%.
We actually checked.

Live cross-venue prices, a calibration-backed edge scanner, and the historical curves behind every number — so “the market thinks 30%” is something you can actually check, not just repeat.

413K
settled markets archived
512K
price–outcome pairs
103
calibration buckets
nightly
updated, before the purge
What Priors does

Measure the market. Measure yourself.

Every other tool helps you place a bet. Priors tells you what the bet — and the bettor — is actually worth.

Live edge scanner

Every open Kalshi market, checked against its calibration bucket in real time. A small badge means we actually found a trustworthy mispricing — most markets won't have one, and that's the honest, common case.

Browse live markets

Cross-venue compare

The same event, priced on Kalshi and Polymarket side by side. See where the two venues actually disagree, not just where headlines say they do.

Compare venues

Calibration explorer

When Kalshi prices something at 30¢, does it happen 30% of the time? The historical curve behind every edge we surface, by category, price, and horizon.

Explore the data
What half a million bets revealed

The market lies in specific places.

Climate · final hour
$5

Bet $100 on final-hour weather longshots and history paid back about $5. Roughly 12× overpriced.

Head-to-head sports
101¢

Buying both sides of a match costs ~101¢ per guaranteed 100¢ — a quarter of a sportsbook's cut.

Sports · 24h · favorites
90.7%

“Sure thing” favorites priced at 95¢ the night before resolve just 90.7% of the time.

We count games, not tickers.

One game spawns forty correlated markets. Every other accuracy dashboard counts them as forty observations — so their error bars lie. We cluster by event and bootstrap over games. It’s the only calibration you can trust.

Where this is going

Built for people who take markets seriously.

Priors started as a calibration engine, and that’s still the core of it: real numbers, checked against what actually happened, no spin. Where we’re headed — analytics and insight for prediction-market traders, and in time, a place to learn from people who know these markets well.