The spread scanner for prediction markets.

Before you pay for this

What you're actually buying

• ArbTrader never trades on its own, on either plan. On Base it's a reporting tool: it shows you the legs, prices, and a link to each one, and you place every trade by hand. On Pro it can submit Kalshi and Polymarket orders, but only after you open the ticket for that specific opportunity, set the size, and confirm it. There is no auto-trade mode, and ArbTrader never places a sportsbook bet on any plan.
• Sending every leg is not the same as locking in the spread. Each leg is its own order — a bundle can have many legs, and they don't fill as one transaction. One-tap tickets send up to 4 legs; bigger bundles you place leg by leg. If a price moves first, one leg can fill while the other doesn't, leaving you with an unhedged position until you close or complete it yourself. ArbTrader doesn't unwind it for you.
• Pro needs keys that can move money. Order tickets require a Kalshi API key with trading permission and your Polymarket signing key, both stored on your own machine. Anyone who can use that machine could use them — secure it accordingly, or stay on Base if you'd rather only ever hold read-only keys.
• Genuine, capturable arbitrage on Kalshi and Polymarket is rare and closes fast. These are liquid markets watched by other bots running similar scans; a spread you see may already be thinner or gone by the time you act. Real-time feeds, Discord alerts, and Pro's order tickets shrink the time between a spread appearing and your orders going out — they don't guarantee a fill at the price you saw.
• Cross-platform and cross-bookmaker matching is only as good as what you personally confirm. A Kalshi-to-Polymarket pairing you haven't verified, or a sportsbook line that's already moved, can turn a "hedge" into an unhedged position. Unconfirmed matches are always shown separately and flagged as needing review — never treated as high-confidence.
• A bundle is only a hedge if exactly one listed outcome wins. We only list events where the platform’s own data says so, but a platform can clarify or change an event’s rules — read them before you trade.
• The sportsbook, real-time WebSocket, and Pro order-submission integrations are built from each platform's own published API documentation, not verified against our own funded live account (we don't run one, and never see yours). Spot-check them against the platform's own numbers the first time you turn each on.
• Fees and size are estimates at the moment we checked. Bundle spreads use Kalshi’s published fee formula and each Polymarket market’s own fee settings, at the size resting at the best price — your fills can differ, and rules or fees can change. Cross-platform and sportsbook spreads in the app still subtract a rough per-leg estimate. Capital sits tied up until the event resolves, so judge a spread by its return over that time, not the raw number.
• Legality and tax treatment of prediction-market trading and sports betting vary by state and country and change often. Confirm you're eligible to use each platform or sportsbook from your location, and that its terms allow API-based trading on your account, before connecting a real one.

Nothing on this page is financial, legal, or betting advice. Past spread detection does not guarantee future opportunities, and trading and betting both involve risk of loss — including total loss of amounts wagered or traded.