Odds comparisonAPI
Prediction Market Odds Comparison: what it does, what it costs, where it stops
Last checked 2026-09-08
This Apify Actor by scrapemint finds the same binary question listed on Kalshi, Polymarket and PredictIt and returns one row per matched pair: the implied YES probability on each venue, the absolute gap, which venue prices YES lower, and whether that gap is wider than both venues' bid-ask spreads.
It is priced per result, $5.00 per 1,000 matched pairs, which is half a cent a row. It had 2 total users when checked, so it is new and lightly tested.
What it does
Each run pulls live snapshots from the three venues, matches questions across them and emits rows with a match confidence score, liquidity data, resolution timing and direct market links. The clears-both-books flag is the useful part: a gap smaller than the combined spread is not a trade.
The listing describes Kalshi as a CFTC-regulated US event-contract exchange, Polymarket as a crypto order book and PredictIt as a US real-money political market. Rows identify the venue pair, so a Kalshi-PredictIt match and a Kalshi-Polymarket match for the same question arrive as separate lines.
- Output: matched question, venue pair, YES probability per venue, absolute spread, cheaper venue, exceeds-book-width flag, confidence, liquidity, resolution timing, links
- First two rows per run are free; a run with no matches emits one free note row
- Categories on Apify: Business, News
Pricing
$5.00 per 1,000 matched cross-venue pairs, charged only on rows returned, plus whatever Apify compute the run consumes. There is no subscription.
Venues and data
Kalshi, Polymarket and PredictIt. The listing warns that PredictIt contracts within an event do not sum to 1 because they are not mutually exclusive, and that PredictIt imposes per-contract position limits, so a PredictIt leg does not behave like a Kalshi or Polymarket leg.
Where it falls short
Two users and no ratings means the matching quality is unproven in public. Check every pair's resolution criteria before acting.
Prices are snapshots at run time. The listing says all three venues move continuously and that fees, slippage and settlement rules differ. It outputs a comparison, not a fee-adjusted trade.
Who should use it
Analysts who want a cross-venue price table on a schedule without building scrapers, especially where PredictIt is one of the venues, since few tools cover it.
Questions about Prediction Market Odds Comparison (Apify)
How much does the Prediction Market Odds Comparison Actor cost?
$5.00 per 1,000 matched pairs, plus Apify compute. The first two rows of each run are free.
Which venues does it compare?
Kalshi, Polymarket and PredictIt.
Does it show fee-adjusted profit?
No. It reports the YES-price gap and whether it exceeds both venues' bid-ask spreads. Fees and slippage are left to you.
Is it the same as the Polymarket + Kalshi Arbitrage Finder?
No. That is a different Actor by a different author, covers two venues, and charges per start rather than per row.
Trackers find the edge. Calculators size it. Alerts time it.
When it is time to execute, the free Kairos terminal trades Kalshi, Polymarket and Predict.fun from one book.