Kalshi & Polymarket Scraper

What does Kalshi & Polymarket Scraper do?

Kalshi & Polymarket Scraper reads Kalshi and Polymarket and returns both in one schema. Every row is a market: the question, the current probability, best bid and ask, total and 24-hour volume, liquidity, open interest, the close date, the resolution once it settles, the trading rules, and a link to the market. Order books are optional, ten price levels a side by default.

Two exchanges with completely different vocabularies. Kalshi quotes cents-on-the-dollar as strings and keeps the category on the event; Polymarket wraps its arrays in JSON strings and keeps categories in event tags. This actor normalises both, so a query returns one table you can sort by probability or volume without writing glue code.

Weather markets, which nobody serves reliably

Kalshi runs a daily temperature market for every major American city, the series KXHIGHNY, KXLOWNY and their siblings. Pick the Weather preset and you get every open temperature market with its strike, probability, close time and, once the day is settled, the measured temperature in settlementValue. The most-used weather actor in this category currently fails 95 percent of its runs and has not been touched since June. Ours is checked every morning by a scheduled run.

Other presets: Politics and elections, Economics and the Fed, Sports, Crypto, Entertainment.

Try it without paying

The first two rows of every run are free, on every plan. Run it, look at the output, then decide. You are billed from the third row onward.

What changed since yesterday

Give the run a watch name or save it as a task, and every run compares itself with the previous snapshot. The CHANGES record lists:

• new markets that opened since the last run,
• markets that settled, with the winning outcome,
• the biggest probability moves, every market that moved by five points or more, sorted by size of the move.

Each row also carries probabilityChange, the move since the last run, so a scheduled task turns into a movers feed. Comparison costs nothing.

Input

{
  "exchanges": ["kalshi", "polymarket"],
  "query": "fed rate",
  "categories": ["Economics", "Politics"],
  "status": "open",
  "minVolumeUsd": 10000,
  "closingWithinDays": 90,
  "maxMarkets": 200,
  "includeOrderBook": false,
  "newOnly": false,
  "watchKey": "macro"
}

Both exchanges list tens of thousands of markets, most of them automated sports contracts with no volume. minVolumeUsd and closingWithinDays are the two filters that make the output readable.

Output

{
  "key": "polymarket:4000554",
  "exchange": "polymarket",
  "marketId": "4000554",
  "question": "Will the Fed cut rates in December?",
  "category": "Economics",
  "tags": ["Economics", "Fed", "Rates"],
  "status": "open",
  "probability": 0.62,
  "probabilityChange": 0.04,
  "yesBid": 0.61,
  "yesAsk": 0.63,
  "outcomes": ["Yes", "No"],
  "outcomePrices": [0.62, 0.38],
  "volumeUsd": 1772232.77,
  "volume24hUsd": 148021.31,
  "liquidityUsd": 155163.59,
  "closesAt": "2026-12-10T17:00:00.000Z",
  "resolvedOutcome": null,
  "url": "https://polymarket.com/event/fed-decision-in-december"
}

Probabilities are on a 0 to 1 scale on both exchanges: a Kalshi contract settles at one dollar, so its YES price is the probability directly.

Pricing

Event	Price
Market returned	$0.004 ($4 per 1,000 markets)
Order book snapshot, only when requested	$0.002
Probability move of five points or more since your last run	$0.010
First two rows of every run	free
Markets removed by filters, markets already seen in new-only mode	free

No start fee. A run that returns nothing costs nothing. For comparison, the most expensive actor in this category charges $0.10 per market record, twenty five times our price, and fails a third of its runs.

Frequently asked questions

Where does the data come from? Kalshi's public trade API and Polymarket's public Gamma and CLOB APIs. Both are official, documented and free, and neither needs a key, a wallet or a login. Nothing is scraped from a web page.

Why do some Kalshi markets show a probability of zero? Because nobody has traded them yet and there is no bid or ask. The field is the last price when there is one, otherwise the midpoint, otherwise null. Nothing is guessed.

Can I compare the same question across both exchanges? The actor returns both in one table with the same fields, so a filter on a keyword gives you Kalshi and Polymarket side by side. Automatic matching of equivalent contracts is not attempted, because the wording and the resolution rules differ and a wrong match is worse than none.

How current is it? Read live at run time. Order books are a snapshot from the moment of the request.

How to use Kalshi Scraper & Polymarket Scraper

1. Open the actor and fill in preset in the input form, or paste the JSON input from the example above.
2. Click Start. The first rows appear in the Output tab within seconds; the run summary is in the Storage tab under the key SUMMARY.
3. Download the results as JSON, CSV or Excel from the Output tab, or read them through the API link shown there.
4. To run it on a schedule, click Save as a task, set the input once and add a schedule. Scheduled tasks keep their own change snapshot, so the new-only mode works without any extra setup.

Integrations

The actor is available in the Apify apps for Make, Zapier, n8n and Keboola, where you pick it by name and map the input fields. It is also exposed to AI agents through the Apify MCP server, and callable from any language through the Apify API; the API tab on this page has ready-made snippets for Node.js, Python and curl. Every run can post its results to a webhook when it finishes.

Support

Questions and problems go into the Issues tab of this actor. Each issue is answered by the maintainer, and fixes ship as new builds without any change on your side.

Built and operated by deriverge s.r.o. Same rules as our other actors: unified schema, honest billing, no charge for what you did not get.