Question 1

What is the GhostLeg Data API?

Accepted Answer

The GhostLeg Data API is a licensed sports betting intelligence API providing signal scores, CLV analytics, sportsbook vs. Kalshi vs. Polymarket three-way divergence signals, sharp money consensus, and line movement data across NBA, NFL, NHL, MLB, UFC, EPL, and NCAAB. Built for developers, quantitative analysts, and sports betting app builders.

Question 2

Does GhostLeg provide Kalshi prediction market data vs sportsbooks?

Accepted Answer

Yes. The GhostLeg Data API tracks Kalshi prediction market implied probabilities against sportsbook consensus in real time, producing a divergence signal when prediction market traders and sportsbooks disagree. The Market Intelligence tier also includes Polymarket divergence, creating a three-way signal: sportsbooks × Kalshi × Polymarket — unique to GhostLeg and not available from any other API provider.

Question 3

What is sportsbook vs prediction market divergence?

Accepted Answer

Sportsbook vs. prediction market divergence occurs when Kalshi or Polymarket prices a sports outcome at a different implied probability than sportsbooks. Prediction markets use an order-book model driven by trader consensus; sportsbooks set fixed odds. Persistent divergence can signal information asymmetry. GhostLeg quantifies this as a signal score for betting models and apps.

Question 4

What is closing line value (CLV) in sports betting?

Accepted Answer

Closing line value (CLV) measures whether a bet was placed at better odds than the closing line — the final price before a game starts. CLV is the most predictive metric of long-term betting edge because the closing line represents the sharpest consensus price. GhostLeg provides CLV analytics segmented by signal score band across all supported sports.

Question 5

How is GhostLeg different from other sports betting APIs?

Accepted Answer

Most sports betting APIs deliver raw odds — the price at a moment. GhostLeg delivers processed intelligence: composite signal scores, CLV analytics, Kalshi and Polymarket prediction market divergence, and sharp consensus via Pinnacle. The three-way divergence signal (sportsbooks × Kalshi × Polymarket) is unique to GhostLeg.

Question 6

How do I access the GhostLeg Data API?

Accepted Answer

Authentication uses an x-api-key header. A public sample endpoint at /api/signals/sample requires no auth. Three tiers: Signal Intelligence (gl_si_), Market Intelligence (gl_mi_), Full Firehose (gl_ff_). Access at ghostleg.ai/data-api.