ProbBrain — Free Live Polymarket & Kalshi Arbitrage Scanner with a Public Track Record
ProbBrain is a free, public dashboard for prediction-market enthusiasts. We do two things: (1) scan Polymarket and Kalshi for live arbitrage opportunities, and (2) publish individual market signals with a transparent track record. Both run automatically, and both are visible at probbrain.com . This post walks through what we just shipped, the numbers behind it, and why we ship our scoreboard publicly even when it makes us look bad. The Live Arbitrage Scanner The scanner runs every 15 minutes against both Polymarket and Kalshi. It surfaces opportunities in three tiers, sorted by net edge after fees: Tier 1 — Actionable. True risk-free arbs after estimated fees. These are rare on purpose and get arbed away in seconds when they appear. Tier 2 — Inconsistencies. Within-Polymarket sum violations, within-Kalshi monotonicity breaks, or cross-platform mismatches that aren't quite risk-free but still represent real mispricings worth watching. Tier 3 — Signals. Lowe...