defi-ape/polymarket-kalshi-arbitrage-bot

This is an automated trading bot written in TypeScript that watches two prediction market platforms, Polymarket and Kalshi, and looks for moments when the same event is priced differently on each platform. When a pricing gap large enough to be worth acting on is detected, the bot can automatically place a buy order on Polymarket. Prediction markets let people bet on the outcome of real-world events, like whether a certain index will be up or down by the end of a 15-minute window. Both Polymarket and Kalshi run these short-duration markets, but because they have different user bases and order books, their prices for the same outcome sometimes diverge. This bot tries to profit from that divergence. The strategy has two rules. The first checks whether Kalshi is pricing a YES outcome between 93 and 96 cents, while Polymarket is pricing the equivalent outcome at least 10 cents cheaper. If both conditions are true after a configurable delay from market open, the bot flags the market as a buy opportunity on Polymarket. The second rule watches for the case where Kalshi has already settled or closed a market while Polymarket still has an active order book, which can occasionally create a late entry opportunity. The bot runs as a small web server with a status endpoint that reports the current pricing from both platforms and whether a buy signal is active. Trading execution is optional: if you configure a Polymarket wallet and API credentials in the environment file, the bot will place orders automatically. If you leave those credentials out, it only monitors and reports signals. Setup requires Node.js 18 or later and a few environment variables: the Kalshi and Polymarket market identifiers for the pair you want to monitor, and optionally your Polymarket wallet details for live trading. The bot is designed to run continuously on a server, a container, or any cloud instance. The README includes a disclaimer that prediction market trading carries real financial risk, and that the bot does not guarantee profit.