PRE-LAUNCH DRAFT · COUNSEL REVIEW REQUIRED
Data Sources and Methodology
Where 9Lines obtains market information, how it is normalized, and what users should verify.
Sportsbook odds
Sportsbook prices are currently obtained through The Odds API using officially exposed aggregation endpoints and venue deep links when supplied. Coverage, update speed, periods, market types, and link support vary by source and subscription.
Prediction markets
Kalshi public market data is obtained through its public market API. Polymarket public market data is obtained through its Gamma market-discovery API. 9Lines preserves native market identifiers, timestamps, rules, and resolution sources when available.
Normalization
Decimal prices may be converted to American odds. Two-way sportsbook probabilities may be normalized to remove the displayed hold for comparison. Prediction-contract prices are shown as market-implied probabilities, not 9Lines forecasts.
Matching methodology
Automatic equivalence requires compatible league, participants, start time, full-game market type, outcome mapping, and sufficient settlement information. Similar titles alone are never enough. Uncertain candidates remain separate and non-actionable pending review.
Freshness and outages
Each actionable quote should display its source timestamp. Feeds may be live, delayed, degraded, or offline. Cached information may remain visible during temporary failures and should not be treated as executable.
Primary references
Corrections
Users and providers may report suspected data, attribution, or matching errors through the legal contact published before production launch. 9Lines may suppress a market while a discrepancy is investigated.
Contact
Legal contact information must be configured and published before production launch.