Prediction Market Arbitrage

Public, no-auth endpoint returning the live cross-venue prediction-market board: the same real-world event priced on Polymarket, Kalshi/Robinhood and PredictIt side by side, with a real arbitrage flagged whenever the combined cost of locking a $1 payout drops under $1 (is_arbitrage=true, with roi_pct and profit_per_dollar). Each opportunity carries both legs (venue, price, direct trade URL) plus when the arb last opened. Refreshed every 30 minutes and CDN-cached ~2 minutes, so polling agents get near-real-time data. Powers the get_arbitrage MCP tool. Informational only, not financial advice.

GEThttps://www.startuphub.ai/api/v1/arbitrage

Request

# Full board, or add ?arbs_only=1 for live arbitrages only
curl "https://www.startuphub.ai/api/v1/arbitrage"

Parameters

arbs_onlystringoptional

Set to "1" or "true" to return only events with a live arbitrage right now (combined cost under $1). Default returns the full matched-events board.

Response

json

{
  "ok": true,
  "matched_events": 7,
  "live_arbitrages": 1,
  "returned": 7,
  "opportunities": [
    {
      "event": "Will X win the 2026 nomination?",
      "resolves": "2026-08-01",
      "is_arbitrage": true,
      "combined_cost": 0.96,
      "profit_per_dollar": 0.04,
      "roi_pct": 4.2,
      "arb_opened_at": "2026-06-14T15:00:00Z",
      "legs": {
        "yes": { "venue": "polymarket", "venue_label": "Polymarket", "price": 0.55, "url": "https://polymarket.com/..." },
        "no":  { "venue": "kalshi", "venue_label": "Kalshi / Robinhood", "price": 0.41, "url": "https://kalshi.com/..." }
      },
      "min_volume": 25000,
      "note": "Both resolve on the same nomination outcome.",
      "startuphub_url": "https://www.startuphub.ai/arbitrage"
    }
  ],
  "venues": ["polymarket", "kalshi", "predictit"],
  "disclaimer": "Informational only, not financial advice...",
  "powered_by": "StartupHub.ai"
}

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