Prediction Markets Scraper – Kalshi & Polymarket

Get Kalshi and Polymarket markets in one clean schema: the question, yes/no probabilities, bid/ask, last price, 24-hour change, volume, liquidity and open interest, close time and the result once resolved. Filter by keyword, category, minimum volume and close date, or turn on only-changed mode to monitor odds over time and pay only for markets that moved.

What data can I get?

Field	Example
source, marketId, eventId	kalshi, KXELONMARS-99, KXELONMARS
eventTitle, marketTitle, marketLabel	Who will the next Pope be?, the market's question, Pietro Parolin
yesPrice, noPrice	0.105, 0.895 (probabilities, 0–1)
outcomes, outcomePrices	["Yes","No"], [0.105, 0.895]
bestBid, bestAsk, lastPrice, priceChange24h	0.10, 0.11, 0.11, -0.02
volume, volume24h, liquidity, openInterest	USD
status, result	open / closed / resolved, winning outcome
openTime, closeTime	ISO dates
category, tags, rules	World, topic tags, resolution rules
url	public market page

Prices are normalised to probabilities on both exchanges, so a Kalshi 11¢ contract and a Polymarket 11% outcome read the same: 0.11.

How much does it cost?

$1 per 1,000 markets. You pay only for markets delivered. A daily snapshot of the 500 busiest markets costs $0.50.

How do I use it?

1. Pick the exchanges (both by default) and the status (open, closed, or all).
2. Optionally filter: a keyword (bitcoin, election, fed), categories, minimum volume, or markets closing within N days.
3. Run, then download JSON, CSV or Excel, or call the API.

{
  "sources": ["kalshi", "polymarket"],
  "search": "bitcoin",
  "status": "open",
  "minVolume": 10000,
  "closesWithinDays": 30,
  "maxItems": 500
}

How do I track odds over time?

Turn on Only changed and schedule the Actor (e.g. every hour). Each run returns a market only if it is new or its price or volume changed since your last run, so a quiet market costs nothing. Every row carries scrapedAt, so the dataset history becomes your price series.

Use cases

• Trading and research: compare the same event across Kalshi and Polymarket and spot price gaps.
• Newsrooms and newsletters: "what the markets say" on elections, the Fed, sports and tech, refreshed daily.
• Data science: resolved markets with their final prices for calibration studies.
• Alerts: only-changed runs piped to Slack or email when odds move.

FAQ

Where does the data come from? From each exchange's official public market-data API (Kalshi trade API v2, Polymarket Gamma API). No login, no trading, no private data.

Is any personal data included? No. No trader profiles, wallet addresses or comments are collected.

How fresh is it? Kalshi is live at run time. Polymarket's API is cached by the exchange for up to 5 minutes.

Why does a keyword search take longer? Kalshi has no server-side search, so the Actor reads every open market and filters them; a narrow search can take a minute or two. You still pay only for the markets returned.

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