FluxrBot Tools
Free calculators and a live radar for prediction markets
Five free tools for anyone trading on Polymarket or Kalshi:
• Live radar — biggest 24h movers and deepest order books on both venues, rebuilt hourly from the exchanges' public APIs
• Payout calculator — profit, ROI and break-even win rate, with Kalshi's exact fee formula applied: 0.07 × contracts × price × (1 − price), rounded up
• Odds converter — probability ↔ contract price ↔ American ↔ decimal, and why the sportsbook version of the same number has margin baked into it
• Kelly calculator — position sizing at full, half and quarter Kelly
• Arbitrage checker — does that cross-venue price gap actually survive fees?
No account, no signup, no paywall, no ads. The radar is worth a look even if you never use the calculators: it's a static page that fetches both venues' APIs at build time and rebuilds every hour, so there's near-live data with no backend running anywhere.
We also build an automated trading bot for these markets, which is how the tools get paid for. It's linked from the site. The tools aren't gated behind it and won't be.
Comments
Maker here. I kept rebuilding the same spreadsheets for prediction market math, so I turned them into pages anyone can use. The radar was the interesting build: a static site that fetches both venues' APIs at build time and rebuilds hourly, so there's near-live data with no backend. Two things surprised me along the way. Kalshi's flat /markets endpoint is mostly noise — thousands of auto-generated multi-leg contracts with zero volume. The liquid markets only come out of /events?with_nested_markets=true, paginated by cursor. And the two venues report volume in different units: Polymarket in USD, Kalshi in contract counts. Compare them directly and Kalshi looks 1000x smaller than it is, which is the opposite of the truth by notional. That's why the radar ranks per venue instead of merging them into one list. If there's a calculator you keep rebuilding yourself, tell me and I'll add it.
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Comments
Maker here. I kept rebuilding the same spreadsheets for prediction market math, so I turned them into pages anyone can use. The radar was the interesting build: a static site that fetches both venues' APIs at build time and rebuilds hourly, so there's near-live data with no backend. Two things surprised me along the way. Kalshi's flat /markets endpoint is mostly noise — thousands of auto-generated multi-leg contracts with zero volume. The liquid markets only come out of /events?with_nested_markets=true, paginated by cursor. And the two venues report volume in different units: Polymarket in USD, Kalshi in contract counts. Compare them directly and Kalshi looks 1000x smaller than it is, which is the opposite of the truth by notional. That's why the radar ranks per venue instead of merging them into one list. If there's a calculator you keep rebuilding yourself, tell me and I'll add it.
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