Prediction Market Odds - Polymarket + Kalshi

Live prediction-market prices from Polymarket and Kalshi in one normalized dataset. Search by keyword, pick a tag or series, or just take the most-traded markets - every row has the question, YES/NO prices (= implied probability), best bid/ask, spread, last trade, 24h and total volume, liquidity, open interest, close time, resolution rules, category/tags and a link back to the market.

Both platforms are read through their official public market-data APIs (Polymarket Gamma API, Kalshi Trade API v2 public endpoints). No account, no API key, no proxies, so runs finish in seconds and are reliable.

What you can do with it

• Track the odds of anything - elections, Fed decisions, crypto price levels, sports, weather, entertainment - on a schedule, into a Google Sheet, Slack alert or your own database.
• Compare platforms - the same question is often listed on both exchanges at different prices; sort by question after a keyword search to spot gaps.
• Research and journalism - historical snapshots (run daily; each row carries fetchedAt) give you probability time series without trading-API access.
• AI agents - give an agent a fast, structured "what does the market think about X?" tool through the Apify MCP server.
• Trading dashboards - volume, liquidity and spread are enough to rank where the action is right now.

Input

Field	Type	Default	Notes
platforms	array	["polymarket","kalshi"]	One or both.
query	string	-	Keyword matched against market/event titles (Polymarket: server-side search; Kalshi: title, subtitle, ticker). Empty = top markets.
maxMarkets	integer	200	Max rows in total. Hard cost cap.
sortBy	volume24h / volume / liquidity / closeTime	volume24h	Order before the cap is applied.
minVolume	number	0	Drop thin markets.
minLiquidity	number	0	Drop markets with a thin order book.
closingWithinDays	integer	0	Only markets closing within N days.
includeClosed	boolean	false	Include resolved / closed markets.
includeRules	boolean	true	Add the resolution rules text.
polymarketTags	array	[]	Polymarket tag slugs, e.g. politics, crypto, sports, fed.
kalshiSeriesTickers	array	[]	Kalshi series, e.g. KXHIGHNY, KXBTCD, KXNFLGAME.
kalshiEventTickers	array	[]	Kalshi events, e.g. KXHIGHNY-26SEP22.
kalshiScanLimit	integer	5000	Open Kalshi markets scanned when no series/event filter is set.

Example input - everything about Bitcoin on both platforms:

{
    "platforms": ["polymarket", "kalshi"],
    "query": "bitcoin",
    "maxMarkets": 100
}

Example input - NYC daily high-temperature markets on Kalshi (a popular weather-trading series):

{
    "platforms": ["kalshi"],
    "kalshiSeriesTickers": ["KXHIGHNY"],
    "sortBy": "closeTime"
}

Output

One dataset item per market (a multi-outcome Polymarket event becomes one row per outcome market; outcomeLabel tells you which).

{
    "platform": "polymarket",
    "marketId": "4052420",
    "ticker": "will-bitcoin-reach-87pt5k-in-september-2026",
    "eventTicker": "what-price-will-bitcoin-hit-in-september-2026",
    "eventTitle": "What price will Bitcoin hit in September?",
    "question": "Will Bitcoin reach $87,500 in September?",
    "outcomeLabel": "↑ 87,500",
    "outcomes": [{ "name": "Yes", "price": 0.805 }, { "name": "No", "price": 0.195 }],
    "yesPrice": 0.805,
    "noPrice": 0.195,
    "impliedProbability": 0.805,
    "bestBid": 0.8,
    "bestAsk": 0.81,
    "spread": 0.01,
    "lastTradePrice": 0.805,
    "volume": 539615.28,
    "volume24h": 221463.49,
    "liquidity": 59695.76,
    "openInterest": null,
    "status": "open",
    "openTime": "2026-09-01T05:07:15Z",
    "closeTime": "2026-10-01T04:00:00Z",
    "resolutionSource": null,
    "rules": "This market will immediately resolve to \"Yes\" if any Binance 1 minute candle for BTC/USDT ...",
    "category": null,
    "tags": ["Bitcoin", "Monthly", "Hit Price", "Crypto", "Crypto Prices", "Recurring"],
    "url": "https://polymarket.com/event/what-price-will-bitcoin-hit-in-september-2026/will-bitcoin-reach-87pt5k-in-september-2026",
    "fetchedAt": "2026-09-21T17:05:41.912Z"
}

Kalshi rows use the same fields: marketId/ticker is the Kalshi market ticker, eventTicker the event, tags holds the series ticker, prices are converted from cents to 0-1, volume/openInterest are in contracts, liquidity in USD.

Pricing

Pay per event:

Event	Price	What it means
Actor start	$0.005	Once per run.
market-result	$0.0015 (= $1.50 per 1,000 markets)	One per market written to the dataset. Markets removed by your filters are free.

A daily snapshot of the top 500 markets on both exchanges costs about $0.76 per run, or ~$23 per month. Comparable single-platform Actors charge $1-10 per 1,000 rows.

Limits and notes

• Prices are a snapshot at fetchedAt; run on a schedule for time series.
• Kalshi has no server-side keyword search. With no kalshiSeriesTickers / kalshiEventTickers, the Actor scans up to kalshiScanLimit open markets and searches locally. For niche topics, pass the series ticker (find it in the Kalshi URL, e.g. kalshi.com/markets/kxhighny/...).
• Polymarket liquidity can be null for markets that have effectively resolved (price at 0 or 1).
• Kalshi url points to the series page (Kalshi market URLs need a human-readable slug that the API does not return); use ticker with the Kalshi API for exact routing.
• Only public market data is read. No trading, no account, no personal data.

FAQ

Why both platforms in one Actor? Because most questions people ask ("what are the odds of X") do not care which exchange lists it, and price differences between the two are themselves interesting.

Can I get order-book depth or price history? Not yet - open an issue if you need it and it will be added as an optional, separately priced event.