Prediction Markets vs Sportsbooks: Live Divergence Board

Where Kalshi and Polymarket prices disagree with the vig-free consensus of the sportsbooks, for the same games, right now. Book consensus comes from the same feed that aggregates 30+ sportsbooks; exchange prices are read from the same store that serves /v1/prediction-markets. A divergence describes where two markets currently disagree; it is not a prediction, a pick, or betting advice.

No qualifying divergences right now: either the pre-game slate is quiet or no event currently trades in both worlds with fresh prices. The board refreshes every 15 minutes; the thresholds a gap must clear are in the methodology below.

Use this table for evaluation. Public display or commercial redistribution requires a separate signed license. Review the terms. Machine formats: /divergence.json and /divergence.rss (RSS 2.0), refreshed on the same 15-minute cache as this page.

Methodology

How this is measured: for every pre-game matchup in 6 major sports we take each sportsbook's latest full-game moneyline snapshot from the last 2 hours, remove the vig by proportional normalization, and take the median implied probability across books, from the same feed that aggregates 30+ sportsbooks; a matchup needs at least 3 books to qualify. We then match the same event on Kalshi and Polymarket by team names and event date within the same sport, and compare the prediction market's latest price for the same outcome (within the last hour), read as an implied win probability. The reported gap is the difference in probability points on the side where the two disagree most; gaps under 1 point are dropped as noise, and games already in play are excluded. Honest caveat: prediction-market prices are not vig-free quotes; they include the exchange's own fees and the bid/ask spread, and a thin order book can sit far from where it would trade at size, so part of any gap is cost structure and liquidity rather than disagreement about the game. All timestamps are UTC. A divergence describes where two markets currently disagree; it is not a prediction, a pick, or betting advice.

Both sides of this board are API calls.

GET /v1/prediction-markets/{sport_key}?sources=kalshi,polymarket serves the exchange prices and GET /v1/sports/{sport_key}/odds the per-book lines behind the consensus. The free tier includes 1,000 credits per month, no card required; paid tiers are listed at /pricing.

curl -s 'https://parlay-api.com/v1/prediction-markets/americanfootball_nfl?sources=kalshi,polymarket' \
  -H "X-API-Key: $PARLAY_API_KEY"

Get a free API key Read the docs

Prediction Markets vs Sportsbooks, Live

Methodology

Related