For those new to prediction markets, an arbitrage lock occurs when you can buy a 'YES' contract on one venue and a 'NO' contract on another for the same real-world event, with their combined cost being less than $1. This guarantees a payout, regardless of the outcome, as one of your contracts will always resolve to $1.
As of August 29, 2026, our engine has surfaced six such opportunities across Polymarket, Kalshi/Robinhood, and PredictIt. These spreads can close rapidly, and potential returns are subject to fees, KYC requirements, and withdrawal limits on each platform. This information is for educational purposes only and is not financial advice.
Track these live, or poll the free API
The board above refreshes on its own, so this page stays current long after today. The full cross-venue feed lives on the arbitrage board, and every match is also a free JSON API and an MCP tool, so a trading agent can poll live Polymarket, Kalshi and PredictIt arbitrage opportunities and act on them.
curl https://www.startuphub.ai/api/v1/arbitrage?arbs_only=1Read the arbitrage API reference or open the live JSON endpoint.
Focused guides: Polymarket arbitrage, Kalshi arbitrage, and the arbitrage bot API.