Sports Prediction Market API (2026): Kalshi, Polymarket, Novig and More

Which prediction markets have sports APIs?

How do you get sports markets from Kalshi and Polymarket?

This Node 18+ script lists upcoming NFL games on Polymarket and NFL game markets with prices on Kalshi, with no keys:

// Polymarket: sports metadata, then upcoming NFL game events
const sports = await (await fetch('https://gamma-api.polymarket.com/sports')).json();
const nfl = sports.find((s) => s.sport === 'nfl');
console.log(sports.length, 'sports on Polymarket; NFL series id', nfl?.series);
const events = await (await fetch(`https://gamma-api.polymarket.com/events?series_id=${nfl.series}&active=true&closed=false&limit=3&order=startDate&ascending=true`)).json();
for (const e of events) console.log('Polymarket |', e.title, '|', e.markets?.length, 'markets');

// Kalshi: open NFL game markets with Yes bid and ask
const K = 'https://external-api.kalshi.com/trade-api/v2';
const { markets } = await (await fetch(`${K}/markets?series_ticker=KXNFLGAME&status=open&limit=4`)).json();
for (const m of markets) console.log('Kalshi |', m.title, '|', m.yes_sub_title, m.yes_bid_dollars, m.yes_ask_dollars);

Why is comparing sports odds across venues hard?

To compare, you have to be sure you are looking at the same bet. That means matching:

• The game: team names and start times written differently on each venue.
• The bet type: moneyline, spread, total, team total, both teams to score or halftime result.
• The period: full game, first half, regulation only.
• The exact line: a spread of −3.5 is not −3.
• The selection: which team or side the price is for.

Get any one wrong and the comparison is meaningless. Prices also need fees added before they are truly comparable, because a cheaper headline price on one venue can cost more after its fee.

How do you compare sports odds across venues in one call?

Predictefy's sports screen lines up each game by bet type, period, line and selection, with one price per venue:

import Predictefy from '@predictefy/sdk';

const client = new Predictefy({ apiKey: process.env.PREDICTEFY_API_KEY });

const games = await client.fetchSportsScreen({ marketType: 'moneyline', limit: 10 });
for (const g of games) {
  console.log(`${g.teams[0].name} vs ${g.teams[1].name}`, g.kickoffAt);
  for (const row of g.market?.selections ?? []) {
    for (const cell of row.cells) {
      console.log('  ', cell.venue, cell.gross?.american, cell.gross?.decimal, cell.gross?.probability);
    }
  }
}

What can you build with a sports prediction market API?

• An odds comparison screen across prediction markets, with best price after fees highlighted.
• Line shopping for traders who want the cheapest entry on each game.
• Prediction market versus sportsbook research, since American odds put both on one scale.
• Live game widgets that show what the markets think as a game unfolds.

Odds are the market's estimate, not a certainty, and trading on sports involves risk.

Frequently Asked Questions