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Prediction Market API Documentation

Use TPM to access Polymarket and Kalshi data, normalize prediction market prices, find cross-platform spreads, and build market-aware products.

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Cross-Platform

Discover events and find price gaps across Kalshi and Polymarket.

Signals

Analyze trending markets, news sentiment, and global API stats.

Live Explorer

Run live requests against the public v2 API schema.

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Create a developer account and issue an API key.

Real response from production APICross-platform spread example

Find live Kalshi/Polymarket price gaps

This request returns real data captured from production. Prices and spreads change over time.

Request
curl 'https://api.thepredictionmarkets.com/api/v2/spreads/top?limit=5&window=24' \
  -H 'X-API-Key: YOUR_TPM_API_KEY'
Response200 OK
{
  "data": [
    {
      "event_slug": "top-artist-on-spotify-us-in-2026",
      "event_title": "Top Artist on Spotify U.S. in 2026?",
      "outcome_title": "Drake",
      "platform_a": "polymarket",
      "platform_b": "kalshi",
      "price_a": 0.1055,
      "price_b": 0.79,
      "spread_bps": 6845,
      "confidence": 0.628,
      "is_stale": false,
      "updated_at": "2026-04-22T02:30:53.049830",
      "platform_a_url": "https://polymarket.com/event/top-spotify-artist-2026",
      "platform_b_url": "https://kalshi.com/markets/kxtopartistusa",
      "matching_strategy": "normalized_title_fallback",
      "match_quality": "auto_medium"
    },
    {
      "event_slug": "which-bills-will-become-law-in-2026-1",
      "event_title": "Which bills will become law in 2026?",
      "outcome_title": "Credit-card routing competition",
      "platform_a": "kalshi",
      "platform_b": "polymarket",
      "price_a": 0.08,
      "price_b": 0.44,
      "spread_bps": 3600,
      "confidence": 0.628,
      "is_stale": false,
      "updated_at": "2026-04-22T02:30:53.049830",
      "platform_a_url": "https://kalshi.com/markets/kxbills",
      "platform_b_url": "https://polymarket.com/event/which-bills-will-become-law-in-2026",
      "matching_strategy": "normalized_title_fallback",
      "match_quality": "auto_medium"
    }
  ],
  "count": 2
}

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Start with Kalshi and Polymarket market data, then add unified spreads, signals, alerts, and watchlists as your workflow grows.

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