Signals

Cross-Platform Spreads

Spread endpoints are the fastest way to find price gaps between Kalshi and Polymarket.

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
}

GET/api/v2/spreads/topTry It

Get top cross-platform spreads

Returns the strongest current Kalshi/Polymarket spread opportunities ranked by confidence. Use this for dashboards and alerts.

Live GET Request

Try it

Request URLX-API-Keylimitwindow

Live Response

Click Try It to run this GET request against the API.

Request

curl 'https://api.thepredictionmarkets.com/api/v2/spreads/top?limit=5&window=24' \
  -H 'X-API-Key: YOUR_TPM_API_KEY'

Response

{
  "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": 0.6845,
      "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"
    }
  ],
  "count": 1
}

Query Parameters

Name	Type	Required	Default	Example	Description
limit	integer	No	20	5	Number of opportunities to return.
window	integer	No	24	24	Freshness window in hours used for top-spread ranking.

Response Fields

Field	Type	Example	Description
event_slug	string	top-artist-on-spotify-us-in-2026	TPM event slug for event detail and history routes.
event_title	string	Top Artist on Spotify U.S. in 2026?	Market or event title.
outcome_title	string	Drake	Outcome being compared across venues.
platform_a	string	polymarket	Platform slug with the lower price.
platform_b	string	kalshi	Platform slug with the higher price.
price_a	number	0.1055	Normalized probability on platform_a (0 to 1).
price_b	number	0.79	Normalized probability on platform_b (0 to 1).
spread	number	0.6845	Absolute price difference as a decimal.
spread_bps	number	6845	Price difference in basis points (spread × 10,000).
confidence	number	0.628	TPM composite score (0–1) factoring spread size, volume, liquidity, and freshness.
is_stale	boolean	false	True when one or both platform quotes exceed the stale cutoff.
updated_at	string	2026-04-22T02:30:53.049830	ISO timestamp of the most recent platform quote.
platform_a_url	string	-	Direct link to the market page on platform_a.
platform_b_url	string	-	Direct link to the market page on platform_b.
matching_strategy	string	-	How the cross-platform match was established: auto_canonical, manual_override, normalized_title_fallback, or event_key.
match_quality	string	-	Match confidence tier: manual, auto_high, or auto_medium.

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