Use case: cross-venue researchers

Compare prediction-market prices against sportsbook consensus

Line Kalshi and Polymarket quotes up against no-vig sportsbook consensus and flag disagreements worth investigating.

Who this is for

Traders and researchers who watch event venues and sportsbooks price the same game differently. The honest framing: these are candidate disagreements to investigate, not asserted arbs, because settlement rules differ across venues.

Recommended workflow
  1. Pull venue prices with /prediction-markets
  2. Pull no-vig consensus for the same games
  3. Compare in probability space, never blended prices
  4. Read each venue's settlement rules before calling anything an arb

The three endpoints this build uses

GET /v1/prediction-markets/{sport_key}Kalshi and Polymarket prices for the sport, one row per source and market, filterable to one venue.
GET /v1/sports/{sport_key}/consensusNo-vig sportsbook consensus in probability space, the fair price you compare a venue quote against.
GET /v1/event-markets/searchFree-text discovery across venues. Returns candidate matches with source-native prices, not asserted equivalence.

Working code

import requests

KEY = {"X-API-Key": "YOUR_KEY"}
BASE = "https://parlay-api.com/v1"

books = requests.get(f"{BASE}/sports/americanfootball_nfl/consensus", headers=KEY).json()
venues = requests.get(f"{BASE}/prediction-markets/americanfootball_nfl",
                      params={"sources": "kalshi"}, headers=KEY).json()
# compare consensus_prob against the venue's own quote per game,
# and read the settlement rules before treating a gap as an arb

Which tier fits

Prediction-market prices are available from the Pro tier up. Event-market search is free in beta, so discovery costs nothing while you scope the build. Current limits are on the pricing page.

Example repo

Start from parlayapi-arb-scanner, an open-source starting point for this exact build.

Build links

/answers/kalshi-prices-api/answers/polymarket-sports-api/use-cases/event-market-radar