Stop guessing on prediction markets.

An arbitrage scanner for prediction markets that runs on the web. Log in at arbtrader.co and your dashboard checks every open Kalshi, Polymarket and Polymarket US event for bundles that pay more than they cost after fees, and shows the legs, prices, size and links. Connect your accounts and it also draws your profit & loss, computed in your browser, from your own trade history. Max adds alerts, Kalshi ↔ Polymarket pairs you confirm, and Kalshi and Polymarket US order tickets you confirm.

All three run the same one-winner bundle scanner across every open Kalshi, Polymarket and Polymarket US event. Base is free and shows you each spread as it appears, with its return and how long it has left, but not the legs, prices, sizes or links; you can watch the scanner work, you just can’t act on it. Pro ($19.99/month) unlocks all of that plus your P&L, and you place the trades yourself. Max ($24.99/month) adds email and Discord alerts, Kalshi ↔ Polymarket pairs you confirm, and one-tap Kalshi and Polymarket US order tickets. International Polymarket legs are placed by you on every plan.

It never opens a trade on its own. On Base and Pro, no; they report opportunities and Pro links you to each leg, and you place every trade by hand. On Max it can send Kalshi and Polymarket US orders, but only when you open the ticket for a specific opportunity, set the size, let it re-check the live prices, and confirm; each leg goes out as a fill-or-kill limit order at the price you approved. The one exception is one you switch on yourself: Auto-sell, which you can arm on a position you already hold so it sells that position once you’d be ahead by the amount you set. It sells while your dashboard is open; when it’s closed, we email you the moment the target is hit so you can sell with one tap. It never buys, fires once and then turns itself off. International Polymarket blocks orders placed from other websites, so those legs are always yours to place.

You do. Your Kalshi private key (and, for Max tickets, your Polymarket US secret) is imported into your browser’s own key store as a non-extractable key: the dashboard can ask the browser to sign a request with it, but neither the page nor we can read the key back out, and it is never uploaded. Each request is signed in your browser and passed through arbtrader.co only because the exchanges’ APIs don’t accept calls from web pages; we forward the signed request and the exchange’s answer, and never see the key. International Polymarket needs only your public wallet address. We never hold your funds on any platform.

Just an ArbTrader account. The live feed works the moment you log in; it uses public market data, not your accounts. A Kalshi API key and your Polymarket wallet address are optional and only power your P&L; on Max, a Kalshi or Polymarket US key with trading permission powers order tickets. Discord alerts need a webhook URL from a server you control. You add all of these on the Connections tab of your dashboard, and you can remove them with one click. Want to look around first? Try the live demo.

The dashboard re-prices every listed spread about once a minute and sweeps all open events in rolling passes, so it can lag the market. Order tickets re-read the live order book the moment before you confirm, and refuse the ticket if the price moved or the size isn't there. Real spreads are rare and close fast; a human confirmation is part of every order by design, and nothing guarantees a fill at the price you saw.

Not on raw speed, and we don’t claim to. Dedicated bots stream every order book and react in milliseconds; ArbTrader re-prices about once a minute and a person confirms every order. Where it earns its keep is the spreads bots tend to skip: cross-platform pairs that need a human to read both sets of rules, newer and quieter venues like Polymarket US, small sizes that aren’t worth a bot’s time, and spreads that tie money up for weeks. It also saves you hours of checking every event by hand.

No. ArbTrader is software that surfaces pricing information across platforms and, on Pro, sends orders you've reviewed and confirmed. Whether to trade, and how much, is always your decision and your risk.

Yes, anytime, including during the trial; you won't be charged unless you're still subscribed when it ends. Switch between Pro and Max from Manage billing on your account page, or drop back to Base for free. It's a monthly subscription with no lock-in.