What is polymarket-kalshi-arbitrage-bot?

This is an automated arbitrage bot for prediction markets, written in TypeScript. Arbitrage means exploiting a price difference for the same thing on two different platforms, if one marketplace prices a "yes" outcome at 95 cents and another prices the same outcome at 82 cents, you can buy the cheaper one and profit when they converge. The bot monitors paired markets on Kalshi and Polymarket, both of which are platforms where you can bet on the outcomes of real-world events (like whether Bitcoin will be higher or lower in 15 minutes). It polls both platforms' APIs on a configurable interval, compares the pricing, and triggers a buy order on Polymarket when the price gap exceeds a threshold you define. It also handles a second scenario: if Kalshi has already settled a market (the event resolved) but Polymarket's order book still has liquidity, it treats that as a late entry opportunity. The bot runs as a lightweight Express web service (Express is a simple Node.js web server framework) that you can deploy on a server or cloud instance. A built-in status API endpoint lets you monitor current prices and the bot's last decision in real time. The tech stack is Node.js 18 or newer, TypeScript, Express, Axios for HTTP calls, and the official Polymarket CLOB client library for order placement. You configure it entirely through environment variables: market identifiers, spread thresholds, wallet credentials for executing trades, and polling intervals. This is aimed at technically-minded traders comfortable running their own server-side automation.