Polymarket & Kalshi API: Prediction Market Odds

Get the live odds of every prediction market on Polymarket and Kalshi in one dataset: the probability of each outcome, how much it moved in the last 24 hours, volume, liquidity, end date and link. Search by keyword (bitcoin, fed, election, nba), filter by category, or catch only the biggest moves of the day.

Straight from both platforms' official public APIs: no login, no API key, no browser. Hundreds of markets in seconds.

Why this one?

• Both platforms, one format. Compare what Polymarket and Kalshi traders think about the same event, side by side.
• Probabilities ready to use. Each outcome's chance in %, plus the 24h move in percentage points, bid, ask and last trade.
• Market movers. Set Min 24h move to get only the markets whose odds jumped, perfect for a daily alert.
• Search the whole catalog. Keywords across every open market (tens of thousands on Kalshi), sorted by 24h volume, total volume, biggest move or closing date.
• Cheap and fast. Pay per market, no subscription.

Use cases

• Traders and arbitrage hunters: compare odds for the same event across Polymarket and Kalshi.
• News and media: cite what markets expect for elections, the Fed, crypto prices, sports and pop culture.
• Research and AI: feed real-time crowd forecasts into dashboards, models or agents.
• Alerts: schedule it hourly or daily and send big moves to Slack, Telegram, email or Google Sheets.

Input

Field	What it does
Platforms	Polymarket, Kalshi or both (default).
Keywords	Only markets about these topics, e.g. bitcoin, fed, election. Empty = the most traded markets.
Categories	Optional: Politics, Crypto, Sports, Economics, Elections, Climate and Weather...
Sort by	Most traded in 24h (default), most traded overall, biggest 24h move or closing soonest.
Max markets per platform	How many markets to keep from each platform, after sorting.
Min total volume	Skip thin markets.
Min 24h move (points)	Only markets whose probability moved at least this much.

{
  "keywords": ["bitcoin", "fed"],
  "sortBy": "volume24h",
  "maxMarketsPerPlatform": 50,
  "minChange24h": 0
}

Output

One row per market (each outcome of a multi-outcome event is its own market):

{
  "platform": "Polymarket",
  "category": "Economy",
  "eventTitle": "Fed Decision in October?",
  "question": "Will there be no change in Fed interest rates after the October 2026 meeting?",
  "outcome": "No change",
  "outcomes": [{"name": "Yes", "price": 0.945}, {"name": "No", "price": 0.055}],
  "probability": 94.5,
  "lastPrice": 0.945,
  "bestBid": 0.944,
  "bestAsk": 0.946,
  "change24h": -1.0,
  "volume": 98500000.0,
  "volume24h": 1803564.35,
  "volumeUnit": "USD",
  "liquidity": 1961748.4,
  "openInterest": null,
  "endDate": "2026-10-29T03:59:00Z",
  "url": "https://polymarket.com/event/fed-decision-in-october",
  "marketId": "0x...",
  "eventId": "fed-decision-in-october",
  "scrapedAt": "2026-10-26T09:26:30Z"
}

• probability is the chance of Yes in %, from the last trade (or the bid/ask midpoint when there's no trade yet).
• change24h is the move of that probability in the last 24 hours, in percentage points.
• Volume is in USD on Polymarket and in contracts on Kalshi (each contract pays $1), see volumeUnit. Kalshi markets have openInterest; Polymarket markets have liquidity.

Good to know

• Only open markets are returned.
• Data comes from the public read-only APIs of each platform. This Actor doesn't place trades and isn't affiliated with Polymarket or Kalshi.
• Prediction markets aren't available to trade in every country. This tool only reads public prices.

Integrations

Schedule it with Apify Schedules and send results to Google Sheets, Slack, Telegram, Discord, Zapier, Make, n8n or your own API.

How to use it

1. Click Try for free (or Start) at the top of this page.
2. Fill in the input, or keep the example to see it working in seconds.
3. Click Start and wait for the run to finish.
4. Download the results as Excel, CSV, JSON or HTML, or get them through the Apify API.

How much does it cost?

$0.002 per market ($2.00 per 1,000). No start fee, no monthly fee, and you only pay for the results saved to your dataset.

Example	Cost
Top 100 markets on both platforms	about $0.40
Hourly movers alert for a month	about $10.00

Apify's free plan includes monthly credit, so you can try it for free.

FAQ

Do I need a Polymarket or Kalshi account?

No. It reads both platforms' public APIs, with no login or API key.

Can I compare the same event on both platforms?

Yes. Search a keyword (for example fed or bitcoin) and both platforms come out in the same format, side by side.

Can I get alerts when odds move a lot?

Yes. Set "Min 24h move" (for example 10 points) and schedule it hourly or daily.

Is volume in dollars?

On Polymarket, yes. On Kalshi it is in contracts, each of which pays $1. The volumeUnit field says which.

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Support

Want price history, order books or another platform? Open an issue on the Issues tab.

If this Actor saves you time, a quick ⭐ review helps a lot and keeps it maintained. Thank you!