Prediction-market & sportsbook spread scanner
ArbTrader watches Kalshi, Polymarket, and sportsbook moneylines around the clock for same-market, cross-platform, and cross-bookmaker spreads — over real-time feeds when available — and lays out the exact legs, prices, and links so you can act on them.
Self-hosted. Runs on your machine, with your own API keys — never ours.
How it works
Run ArbTrader on your own machine and add your Kalshi and Polymarket API keys. They stay local — we never see them.
Same-market, cross-platform, and cross-bookmaker spreads populate as they're detected — over real-time WebSocket feeds when available, with an optional Discord ping the instant one clears your threshold.
Every opportunity shows the exact contracts, prices, sizes, and a direct link to each leg — nothing is confirmed or submitted for you.
Click through and place each leg by hand, directly on Kalshi, Polymarket, or the sportsbook. ArbTrader never submits an order or a bet on your behalf — it never has that code path.
What it detects
One platform, one market: every outcome summed costs less than $1. This is arbitrage by construction — same contract, same resolution rules, no judgment call involved.
A Kalshi market and a Polymarket market that look like the same real-world event. ArbTrader surfaces title-similarity matches for you to inspect and confirm before they're tradable.
One game, two sportsbooks: the cheapest price on one team from one book plus the cheapest price on the other team from a different book costs less than $1 combined. Same game, same clock — just priced differently by different bookmakers.
Before you pay for this
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.
Pricing
ArbTrader license
3-day free trial3 days free, then $45/month, billed via Stripe. Cancel anytime. Runs entirely on your own machine — your API keys and funds never touch our servers.
FAQ
A spread scanner for prediction markets and sportsbooks. It watches Kalshi, Polymarket, and sportsbook moneylines for same-market, cross-platform, and cross-bookmaker spreads and shows you the exact opportunity — the legs, the prices, the links — the moment it finds one, with optional Discord alerts so you don't have to watch the dashboard.
No, never. ArbTrader only reports — it shows you an opportunity and links you to each leg. You review it and execute it yourself, by hand, directly on Kalshi, Polymarket, or the sportsbook, in your own account. There is no code path in ArbTrader that submits an order or a wager.
No. ArbTrader is self-hosted: you run it on your own computer or server, and your Kalshi API key and Polymarket wallet key stay there. We never receive, store, or have access to either.
None to start — ArbTrader runs against bundled sample data with zero accounts or keys, including a sample sportsbook example, just to see how it works. To see real prices you'll want a Kalshi account and/or a Polymarket wallet address, and a free API key from The Odds API for sportsbook lines. Discord alerts need a webhook URL from a Discord server you control. Every one of these is optional and independent of the others.
Kalshi and Polymarket order books stream over WebSocket when configured, which is sub-second — well beyond what polling can do. Sportsbook odds refresh on a slower, credit-budgeted schedule (see the setup docs). Either way, ArbTrader gets you the information fast; placing the trade or bet is still a manual step you do yourself, so speed helps you catch more of what's real, not skip that step.
No. ArbTrader is software that surfaces pricing information across two platforms. What you do with that information — if anything — is your decision and your risk.
Yes, anytime, including during the trial — you won't be charged unless you're still subscribed when it ends. It's a monthly license with no lock-in after that.