Prediction Market Odds: Kalshi, Polymarket, PredictIt

Live prediction-market odds from Kalshi, Polymarket and PredictIt in one dataset, with each 2026 US midterm race matched across venues: one row per race showing each venue's probability, the consensus and where the venues disagree.

Built for traders looking for cross-venue spreads, journalists and newsletters tracking the midterms, campaigns and analysts, and AI agents that need current odds.

What you get

• Every midterm race in one run: House and Senate control, every Senate race, every Governor race and about 430 House districts, as of October 2026.
• Cross-venue matching: the same race on Kalshi, Polymarket and PredictIt mapped to one race ID, e.g. 2026-SENATE-GA or 2026-HOUSE-ME-02.
• Consensus and spread: the average probability per party plus the gap between venues. Filter by minSpread to find disagreements, e.g. Kalshi 80% against PredictIt 50%.
• Candidates: candidate names where the venues list them.
• Search mode: search any topic (bitcoin, Fed rates, Ukraine, impeachment, sports) across venues, most-traded first. Manifold is included as a play-money option.
• Fast and cheap: official public APIs, no login, no proxy. A full midterm run takes about 25 seconds.
• Strictly neutral: every party and race is covered the same way.

Example: midterms mode

{ "mode": "midterms", "offices": ["SENATE", "HOUSE-CONTROL", "SENATE-CONTROL"], "minVenues": 2 }

Output row:

{
  "type": "race",
  "raceId": "2026-SENATE-TX",
  "race": "Texas Senate 2026",
  "office": "SENATE",
  "state": "TX",
  "democratProbability": {"kalshi": 0.635, "polymarket": 0.605, "predictit": 0.61},
  "democratConsensus": 0.6167,
  "democratSpread": 0.03,
  "democratCandidates": ["James Talarico"],
  "republicanProbability": {"kalshi": 0.375, "polymarket": 0.385, "predictit": 0.405},
  "republicanConsensus": 0.3883,
  "favorite": "D",
  "venues": ["kalshi", "polymarket", "predictit"],
  "maxSpread": 0.03,
  "urls": {"kalshi": "https://kalshi.com/markets/...", "polymarket": "https://polymarket.com/event/...", "predictit": "https://www.predictit.org/markets/detail/..."}
}

Probabilities are the mid-point of bid and ask when the book is tight, otherwise the last traded price, on a 0–1 scale.

Example: search mode

{ "mode": "search", "searchQuery": "Fed rate", "venues": ["kalshi", "polymarket", "manifold"] }

Each market row has venue, question, outcome, probability, bid, ask, lastPrice, volume, closeTime and url.

Pricing

• $2 per 1,000 race rows (a full midterm board of about 500 races costs about $1)
• $0.80 per 1,000 market rows

No start fee. You can set a maximum cost per run.

Tips

• Schedule it hourly or daily to build a time series of odds.
• minVenues: 3 gives the races where all three venues have markets, which is best for comparing.
• Kalshi lists far more House districts than the other venues, so those rows often show one venue only.

Disclaimer

This is market data for information and research, not betting or financial advice. Prices change constantly; check them on the venue before acting. Use each venue's data in line with its terms.

Questions: open an issue or email hello@weirworks.com.

Independent tool by weirworks. Not affiliated with Kalshi, Polymarket, PredictIt or Manifold.