Kalshi x Polymarket Arbitrage Scraper

What does Kalshi x Polymarket Arbitrage Scraper do?

This Actor pairs every open market on kalshi.com with the market on polymarket.com about the same event. It then prices each pair off both live order books. You get the best ask on each leg, the size resting at it, both taker fees, and the net edge per $1 contract. You also get the contracts that stay profitable down the books, the capital needed, and the expected profit. Every pair carries a match confidence with its evidence. Every pair also carries a resolution-risk rating with named reasons: settlement source, timing, weather station, strike boundary. A pair is only risk-free if both venues settle it the same way. No Kalshi login is needed.

How to use this actor

• 👉 Register for a free Apify account — no credit card required.
• 🎉 Just click Sign up free on Apify → and complete a quick signup.
• 💰 A free Apify account includes $5 in monthly credits — enough to test this actor.
• ⏳ Scrape during the free trial, with no commitment or upfront payment required.

Key features

• 📖 Priced off both order books: every pair is priced at the ASK you can actually buy at on each venue, not last trade or mid — and walked down both books to show how many contracts stay profitable, the capital needed and the profit, so a 3-cent edge on two contracts is never mistaken for a trade.
• 🧾 Both venues' fees, read live: kalshi's per-series taker fee and Polymarket's per-market fee schedule are read on every run and subtracted before anything is called an arbitrage. Nearly every Polymarket market now charges a taker fee; an edge that ignores it reports the fee as profit.
• 🎯 Matching you can audit: different strike, different settlement date, different candidate, different question about the same company — each is a hard veto before any similarity score. Every pair ships with a confidence score and the evidence behind it, and "above vs below" pairs are priced from the correct side.
• ⚖️ Resolution-risk rating: A pair is only risk-free if both venues settle it the same way. Each pair is rated low / medium / high from differences in settlement source, timing, time zone and oracle status, with the named reasons and both venues' rules text on the row.
• 🔓 No Kalshi login: uses only the venues' public market data. You never hand over a Kalshi email or password.
• ♻️ Incremental mode: recurring runs emit and charge only for listings that are new or whose tracked content changed. First run builds the baseline; subsequent runs emit only NEW / UPDATED / REAPPEARED records (UNCHANGED + EXPIRED opt-in). Saves 80–95% on daily monitoring.
• 🔔 Notifications: Telegram, Slack, Discord, WhatsApp Cloud API, and generic webhook out of the box. Pair with incremental for daily new-listing alerts without pipeline glue.
• 📦 Compact mode: AI-agent and MCP-friendly payloads with core fields only.
• 🧹 Empty-field stripping: drop null, empty-string, and empty-array fields from each record before push. Smaller payloads for AI agents and dashboards that already handle missing fields gracefully.
• 📤 Export anywhere: Download the dataset as JSON, CSV, or Excel from the Apify Console, or stream live via the Apify API and integrations (Make, Zapier, Google Sheets, n8n, …).
• 🔌 MCP connectors: export your results into Notion via Apify's MCP connectors — a clean run-summary page, no glue code. Opt-in via the App connector field; deterministic field-mapping, no AI. Built on Apify's connector framework, so more destinations open up as their catalog grows.

What data can you get for each market pair?

Each result includes Core arbitrage pair fields (pairId, isArbitrage, buyOnKalshi, buyOnPolymarket, kalshiAsk, polymarketAsk, kalshiAskSize, and polymarketAskSize, and more). In standard mode, all fields are always present — unavailable data points are returned as null, never omitted. In compact mode, only core fields are returned.

Input

The main inputs are a result limit. Additional filters and options are available in the input schema.

Key parameters:

• arbitrageOnly — Only return pairs that make money after fees on both venues at the current best asks. Off: return every matched pair, the tradeable ones first, each still marked with isArbitrage. (default: false)
• minNetReturnPct — With Arbitrage Only: skip opportunities returning less than this, after fees, on the capital they tie up. 0 = any positive return. (default: 0)
• maxInvestmentUsd — Size each opportunity up to this much capital. 0 = as deep into both order books as the trade stays profitable. (default: 0)
• maxResolutionRisk — A pair is only risk-free if both venues settle it the same way. Each pair is rated low / medium / high from differences in settlement source, timing and time zone. low means none of those checks fired. It never means zero risk. (default: "high")
• minMatchConfidence — How sure the pairing must be that the two markets are the same event (0.5–1). The score ranks pairs; it is not a probability. Every pair carries the evidence behind it in matchEvidence. (default: 0.72)
• dateToleranceDays — How far apart the two markets' settlement dates may be and still count as one contract. A weekly and a year-end market on the same question are different bets. (default: 7)
• maxResults — Maximum pairs to return. Tradeable pairs come first, and among them the pairs whose settlement terms agree rank above the ones that simply pay more. Every run scans both venues in full whatever this is set to; it only caps how many pairs are delivered. (default: 100)
• descriptionMaxLength — Truncate each venue's settlement-rules text (kalshiRules / polymarketRules) to N characters. 0 = no truncation. (default: 0)
• compact — The trade and nothing else: direction, prices, edge, size, profit, confidence and risk (for AI-agent/MCP workflows). (default: false)
• excludeEmptyFields — Drop null / empty-string / empty-array fields from each output record. (default: false)
• incrementalMode — Compare against the previous run: emit only pairs that are new or whose trade changed (direction, edge to the cent, size, arbitrage status or risk). Built for scheduled monitoring. (default: false)
• stateKey — Optional. Stable identifier for the tracked set of pairs. Leave empty to derive it from your filter settings.
• ...and 15 more parameters

Input examples

Incremental tracking — Only emit arbitrage pairs that changed since the previous run with this stateKey.

→ First run builds the baseline state. Subsequent runs emit only records that are new or whose tracked content changed. Set emitUnchanged: true to include unchanged records as well.

{
  "maxResults": 200,
  "incrementalMode": true,
  "stateKey": "kalshi-tracker"
}

Compact output for AI agents — Return only core fields for AI-agent and MCP workflows.

→ Small payload with the most important fields — ideal for piping into LLMs without token overhead.

{
  "maxResults": 50,
  "compact": true
}

Output

Each run produces a dataset of structured arbitrage pair records. Results can be downloaded as JSON, CSV, or Excel from the Dataset tab in Apify Console.

Example arbitrage pair record

{
  "pairId": "KXHURPATHHAWAII-26DEC|3081724",
  "isArbitrage": true,
  "buyOnKalshi": "YES",
  "buyOnPolymarket": "NO",
  "kalshiAsk": 0.1,
  "polymarketAsk": 0.84,
  "kalshiAskSize": 30.93,
  "polymarketAskSize": 255,
  "grossEdge": 0.06,
  "kalshiFeePerContract": 0.0063,
  "polymarketFeePerContract": 0.00672,
  "netEdge": 0.04698,
  "netReturnPct": 4.9296,
  "settlesInDays": 111.3,
  "annualizedReturnPct": 16.17,
  "maxContracts": 1451.55,
  "capitalRequiredUsd": 1415.99076,
  "expectedProfitUsd": 35.55924,
  "avgKalshiPrice": 0.109787,
  "avgPolymarketPrice": 0.852587,
  "reverseNetEdge": -0.121937,
  "matchConfidence": 0.857,
  "orientation": "direct",
  "matchEvidence": {
    "anchors": [
      "hurricane",
      "make",
      "landfall",
      "hawaii"
    ],
    "textScore": 0.667,
    "dateGapDays": 0,
    "datePlaceholder": false,
    "kalshiThreshold": 2027,
    "polymarketThreshold": 2027,
    "kalshiPolarity": "before",
    "polymarketPolarity": "before"
  },
  "resolutionRisk": "low",
  "settlementGapHours": 0,
  "kalshiSettlementSources": [
    "accuweather.com",
    "nbcnews.com",
    "apnews.com",
    "noaa.gov",
    "wsj.com",
    "... 8 more items"
  ],
  "kalshiTicker": "KXHURPATHHAWAII-26DEC",
  "kalshiEventTicker": "KXHURPATHHAWAII-26DEC",
  "kalshiSeriesTicker": "KXHURPATHHAWAII",
  "kalshiTitle": "Will a hurricane make landfall in Hawaii during the 2026 hurricane season?",
  "kalshiEventTitle": "Will a hurricane make landfall in Hawaii in 2026?",
  "kalshiOutcome": "Before 2027",
  "kalshiCategory": "Climate and Weather",
  "kalshiUrl": "https://kalshi.com/markets/kxhurpathhawaii",
  "kalshiCloseTime": "2027-01-01T04:59:00Z",
  "kalshiRules": "If a 74 mph or higher hurricane makes landfall in Hawaii during the 2026 hurricane season, then the market resolves to Yes.",
  "kalshiVolume": 84366.12,
  "kalshiFeeType": "quadratic",
  "kalshiFeeMultiplier": 1,
  "polymarketMarketId": "3081724",
  "polymarketQuestion": "Will a hurricane make landfall in Hawaii before 2027?",
  "polymarketEventTitle": "Will a hurricane make landfall in Hawaii before 2027?",
  "polymarketUrl": "https://polymarket.com/event/will-a-hurricane-make-landfall-in-hawaii-before-2027-20260721182828397",
  "polymarketEndDate": "2027-01-01T04:59:00Z",
  "polymarketRules": "This market will resolve to \"Yes\" if any storm makes landfall in the State of Hawaii at Category 1 strength or higher, as reported in official Central Pacific Hurricane Center advisories (https://www....",
  "polymarketConditionId": "0x594753f5921304616f36fecd01677e5bf2f6f42a1093fa65e2cdff7193b43ffc",
  "polymarketYesTokenId": "35060136240132571395133165793544488174574304926549949902253752591503618653125",
  "polymarketNoTokenId": "99800683031715173270599094797879828927663082652293813937965741621476641062245",
  "polymarketVolume": 34973.674494,
  "polymarketMinOrderSize": 5,
  "polymarketFeesEnabled": true,
  "polymarketFeeRate": 0.05,
  "kalshiBookRetrieved": true,
  "polymarketBookRetrieved": true,
  "scrapedAt": "2026-09-11T20:39:12.326Z",
  "source": "kalshi-polymarket",
  "contentHash": "a19445859c37bf2c",
  "portalUrl": "https://polymarket.com/event/will-a-hurricane-make-landfall-in-hawaii-before-2027-20260721182828397"
}

Incremental fields

When incremental mode is on, each record also carries:

• changeType — one of NEW, UPDATED, UNCHANGED, REAPPEARED, EXPIRED. Default output covers NEW / UPDATED / REAPPEARED; set emitUnchanged: true or emitExpired: true to opt into the others.

How to scan market pairs

1. Go to Kalshi x Polymarket Arbitrage Scraper in Apify Console.
2. Configure the input.
3. Set maxResults to control how many results you need.
4. Click Start and wait for the run to finish.
5. Export the dataset as JSON, CSV, or Excel.

Use cases

• Extract arbitrage pair data from Kalshi & Polymarket for market research and competitive analysis.
• Track pricing trends across regions and categories over time.
• Monitor new and changed arbitrage pairs on scheduled runs without processing the full dataset every time.
• Feed structured data into AI agents, MCP tools, and automated pipelines using compact mode.
• Export clean, structured data to dashboards, spreadsheets, or data warehouses.

How much does it cost to scan market pairs?

Kalshi x Polymarket Arbitrage Scraper uses pay-per-event pricing. You pay a small fee when the run starts and then for each result that is actually produced.

• Run start: $0.05 per run
• Per result: $0.002 per arbitrage pair record

Example costs:

• 10 results: $0.07
• 25 results: $0.1
• 100 results: $0.25
• 200 results: $0.45
• 500 results: $1.05

Example: recurring monitoring savings

These examples compare full re-scrapes with incremental runs at different churn rates. Churn is the share of arbitrage pairs that are new or whose tracked content changed since the previous run. Actual churn depends on your query breadth, source activity, and polling frequency — the scenarios below are examples, not predictions.

Example setup: 250 arbitrage pairs per run, daily polling (30 runs/month). Costs scale linearly with the number of arbitrage pairs.

Churn rate	Full re-scrape run cost	Incremental run cost	Savings vs full re-scrape	Monthly cost after baseline
5% — stable niche query	$0.55	$0.08	$0.48 (86%)	$2.25
15% — moderate broad query	$0.55	$0.13	$0.43 (77%)	$3.75
30% — high-volume aggregator	$0.55	$0.20	$0.35 (64%)	$6.00

Full re-scrape monthly cost at the same cadence: $16.50. First month with incremental costs $2.73 / $4.17 / $6.35 for the 5% / 15% / 30% scenarios because the first run builds baseline state at full cost before incremental savings apply.

Platform usage is included in the per-result fee shown above.

FAQ

How many market pairs can I check per run?

Every market pair in your input list is checked — there is no fixed cap, so the number of market pairs per run is limited only by your list size and the run's time budget.

Does Kalshi x Polymarket Arbitrage Scraper support recurring monitoring?

Yes. Enable incremental mode to only receive new or changed arbitrage pairs on subsequent runs. This is ideal for scheduled monitoring where you want to track changes over time without re-processing the full dataset.

Can I integrate Kalshi x Polymarket Arbitrage Scraper with other apps?

Yes. Kalshi x Polymarket Arbitrage Scraper works with Apify's integrations to connect with tools like Zapier, Make, Google Sheets, Slack, and more. You can also use webhooks to trigger actions when a run completes.

Can I use Kalshi x Polymarket Arbitrage Scraper with the Apify API?

Yes. You can start runs, manage inputs, and retrieve results programmatically through the Apify API. Client libraries are available for JavaScript, Python, and other languages.

Can I use Kalshi x Polymarket Arbitrage Scraper through an MCP Server?

Yes. Apify provides an MCP Server that lets AI assistants and agents call this actor directly. Use compact mode, descriptionMaxLength, and excludeEmptyFields to keep payloads manageable for LLM context windows.

Is it legal to scan market pairs?

This actor queries publicly available data for the market pairs you provide. You remain responsible for ensuring your use complies with applicable laws, source terms, and downstream obligations.

Your feedback

If you have questions, need a feature, or found a bug, please open an issue on the actor's page in Apify Console. Your feedback helps us improve.

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Getting started with Apify

New to Apify? Create a free account with $5 credit — no credit card required.

1. Sign up — $5 platform credit included
2. Open this actor and configure your input
3. Click Start — export results as JSON, CSV, or Excel

Need more later? See Apify pricing.

Disclaimer

This actor accesses only publicly available data on kalshi.com. You are responsible for how you use the extracted data — in particular any personal information such as names, phone numbers, or email addresses — and for complying with Kalshi x Polymarket Arbitrage's terms of use, applicable data-protection law (including the GDPR where it applies), and the anti-spam rules of your jurisdiction.

This actor is not affiliated with, endorsed by, or connected to Kalshi x Polymarket Arbitrage.

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