For those new to the concept, an arbitrage lock in prediction markets occurs when buying a 'YES' share on one platform and a 'NO' share on another for the same event totals less than $1, guaranteeing a profit regardless of the outcome. These spreads are dynamic and can close rapidly, so immediate action is often required to capitalize on them. Potential profits can also be impacted by platform fees, Know Your Customer (KYC) requirements, and withdrawal limits.
As of July 28, 2026, StartupHub.ai's cross-venue engine has identified five such arbitrage opportunities across Polymarket, Kalshi/Robinhood, and PredictIt. These opportunities allow for a guaranteed payout, with the most attractive spreads offering significant returns on investment.
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.