Polymarket arbitrage scanner
Live Polymarket arbitrage opportunities, matched against Kalshi, Robinhood and PredictIt, with the spread flagged the moment combined cost drops under $1.
Polymarket arbitrage is when the price of a Yes and a No outcome for the same event add up to less than $1.00, so buying both locks a guaranteed $1 payout for less than a dollar and pockets the difference. It comes in two shapes. Internal (bundle) arbitrage happens inside one Polymarket market when its own Yes and No sum under $1 (Yes at 60¢ plus No at 38¢ is 98¢, a locked 2¢). Cross-platform arbitrage is the same real-world event priced differently on Polymarket versus Kalshi, Robinhood or PredictIt: buy the cheap Yes on one venue and the cheap No on the other.
This scanner watches Polymarket alongside the other venues, normalizes every market to a single Yes/No price (the cost of a $1 payout), confirms the two markets resolve on identical criteria, and flags the pair the instant the combined cost slips under $1. It refreshes every 30 minutes, and each live arb comes with a step-by-step walkthrough so you can see exactly which leg to buy where.
The edges are usually small and short-lived, and gas, fees, thin order-book depth and slight differences in how each venue resolves an event all eat into the spread. That is why this is a scanner, not a promise: it surfaces the real, verified mismatches so you can move fast, and feeds a free API and MCP tool if you would rather a bot watch them for you.
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Free arbitrage API and MCP tool for bots
Every match on this page is also a free JSON endpoint and an MCP tool, so a trading bot or AI agent can poll live opportunities and act on them without scraping each venue.
Questions
- What is Polymarket arbitrage?
- Buying opposing outcomes for a combined price under $1 so the $1 payout is locked no matter how the event resolves. It is either a bundle (Yes and No inside one Polymarket market) or cross-platform (the same event cheaper on Polymarket than on Kalshi/PredictIt, or vice versa).
- Is arbitrage allowed on Polymarket?
- Yes. Buying mispriced shares is ordinary trading, not against Polymarket rules. The real limits are practical: liquidity at the mispriced level is thin, so large size is hard to fill, and Polymarket restricts some jurisdictions (including the US), so confirm your own eligibility.
- Is Polymarket arbitrage profitable?
- Spreads are typically 1-5% and fleeting. Bots capture the obvious ones in milliseconds, and gas plus fees can erase a thin edge. It can pay on real, verified mismatches with fast execution, which is what this scanner surfaces, but it is not free money.
- Is there a Polymarket arbitrage bot or scanner?
- This page is a live scanner. For a bot, point it at the free JSON API (
/api/v1/arbitrage) or theget_arbitrageMCP tool, which return the same matched pairs and live prices so an agent can poll and act without scraping Polymarket directly. - Polymarket vs Kalshi arbitrage: what is the difference?
- Kalshi (and Robinhood, which trades on Kalshi’s exchange) is a US-regulated venue; Polymarket is crypto-settled. The same event often prices a few cents apart between them, which is the cross-platform arb this board matches side by side.