Arbitrage
Prediction market arbitrage finders and scanners
Arbitrage scanners and finders that surface Kalshi vs Polymarket spreads, compared on refresh rate, fee handling, pricing and the execution gap each one leaves.
Checked September 8, 2026 · every price read off the live site
Every arbitrage tool
7 reviewed · alphabetical-
Kairos Cross-venue trading terminal: Kalshi, Polymarket and Predict.fun in one order book, with sub-second data and advanced order types.
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ArbBets 990+ matched market pairs, claims 100+ arbs daily at 2 to 8% spreads, API access.
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ArbiTrack Scanner refreshing every 3 minutes, flags 5 to 20 cent gaps across three venues.
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DefiRate Fed odds Fed-decision lines side by side with fee-adjusted expected earnings per contract.
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event-contract-arbitrage Open-source arb scanner if you would rather run your own.
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EventArb Free manual arb calculator with fee-adjusted risk-free setups, plus email alerts.
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Polymarket + Kalshi Arbitrage Finder Running a scheduled Polymarket versus Kalshi scan from Apify and getting a dataset of spreads without hosting anything.
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| Tool | Venues | Pricing | Type |
|---|---|---|---|
| ArbBets | Polymarket, Kalshi, Opinion, Novig | Basic $59 per month. | web app |
| ArbiTrack | Polymarket, Kalshi, PredictIt | Free tier with 5 markets and edges locked. | web app |
| DefiRate Fed odds | Kalshi, Polymarket, Polymarket US, Gemini Predictions, ForecastEx, OG | Free. | dashboard |
| event-contract-arbitrage | Kalshi, Polymarket, Robinhood | Open source. | web app |
| EventArb | Kalshi, Polymarket, Robinhood, Interactive Brokers | Free. | web app |
| PMXT Live Arbitrage Scan | Polymarket, Kalshi, Limitless, Opinion | Open source, no license file. | CLI |
| Polymarket + Kalshi Arbitrage Finder | Polymarket, Kalshi | Pay per event and usage on Apify: $0.05 per Actor start plus Apify platform usage. | API |
How these tools work
Arbitrage finders look for the same event priced differently on two venues, so that buying YES on one and NO on the other costs less than $1 combined. The tools in this category range from a free hand calculator (EventArb) to always-on scanners with alerts and an API (ArbBets from $149 per month for prediction markets, ArbiTrack from $4 a day, Oddpool's scanner where still available) to open-source code you run yourself.
Every one of them stops at the same line: they find the gap. None of them place both legs. The gap you see is also gross in every tool checked except where a fee-adjusted figure is explicitly stated, and Kalshi taker fees, Polymarket gas, slippage and the time between your two orders decide whether a 3 cent spread is real.
Choose by how you trade. If you watch the books yourself, a calculator is enough. If you want to be pinged, pay for a scanner and treat its daily-opportunity counts as marketing until you have logged your own fills.
How to choose
- Venue pairs you can actually trade from your jurisdiction: Polymarket blocks US orders, Kalshi is US only, PredictIt has position limits.
- Refresh rate: ArbiTrack polls every 3 minutes, Oddpool every 30 seconds, EventArb not at all. Faster costs more.
- Fee treatment: prefer tools that state fee-adjusted spreads (ArbBets, Oddpool) over tools that show raw gaps and tell you to do the math.
- Match verification: keyword matching produces false pairs. Look for a similarity score or a manual-check flag, and read both resolution criteria before placing anything.
- Cost against captured spread: a $149 per month scanner needs to clear $149 in net fills before it is worth more than a $4 day pass.
Questions about arbitrage tools
What is the best free prediction market arbitrage scanner?
Prediction Hunt's arbitrage page and ArbiTrack's free tier both show live cross-venue gaps at no cost, with ArbiTrack hiding edge sizes until you pay $4. EventArb is free but manual.
Is prediction market arbitrage between Kalshi and Polymarket risk free?
No. Prices move between your two orders, Kalshi charges taker fees, Polymarket legs cost gas, and resolution criteria can differ between venues. Scanners find candidates; the risk lives in execution.
Which arbitrage tools have an API?
ArbBets on its $299 Premium tier, Prediction Hunt with a free API tier and an arbitrage WebSocket channel, and Oddpool's Arbitrage API on tiers currently closed to new subscribers. The Apify Actors return datasets you can pipe anywhere.
Trackers find the edge. Calculators size it. Alerts time it.
When it is time to execute, the free Kairos terminal trades Kalshi, Polymarket and Predict.fun from one book.