Maker here. I trade prediction markets and kept rebuilding the same spreadsheets — what's the fee on this Kalshi contract, what's the break-even, how much should this position actually be. So I turned them into pages anyone can use. The part that was actually interesting to build is the radar. It's a static site that fetches both exchanges' public APIs at build time and rebuilds every hour, so you get near-live data with zero backend. Two things surprised me while building it: 1. Kalshi's flat /markets endpoint is almost all noise — thousands of auto-generated multi-leg contracts with zero volume. The liquid markets only surface through /events with nested markets, paginated by cursor. 2. The two venues report volume in different units. Polymarket gives dollars, Kalshi gives contract counts. Compare them directly and Kalshi looks 1000x smaller than it is, which is the opposite of the truth. Everything's free with no signup. Full disclosure: we also build a paid trading bot, and that's linked from the site — but the tools aren't gated and won't be. If there's a calculator you keep rebuilding yourself, tell me and I'll add it.

FluxrBot Tools

Free calculators and a live radar for prediction markets

Free calculators and a live radar for prediction markets