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from $5.00 / 1,000 matched pairs

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Polymarket vs Kalshi Matched Markets & Price Gaps

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Finds the same question listed on both Polymarket and Kalshi - election odds, politics, crypto, sports - and reports both prices side by side with the gap and the cross-venue edge each way. Public APIs, no login. Matches are heuristic and carry a similarity score.

Pricing

from $5.00 / 1,000 matched pairs

Rating

0.0

(0)

Developer

John Rutherford

Actor stats

Bookmarked

Total users

Monthly active users

4 days ago

Last modified

What you get

One row per matched pair:

Field	Meaning
`polymarket_question`, `polymarket_url`, `polymarket_event`	The Polymarket market
`kalshi_title`, `kalshi_subtitle`, `kalshi_ticker`, `kalshi_category`	The Kalshi event and the specific leg
`poly_yes_mid`, `poly_best_bid`, `poly_best_ask`	Polymarket YES price (0 to 1)
`kalshi_yes_mid`, `kalshi_yes_bid`, `kalshi_yes_ask`, `kalshi_last`	Kalshi YES price (0 to 1)
`price_gap`	`poly_yes_mid - kalshi_yes_mid`
`edge_buy_kalshi_yes_sell_poly`	`poly_best_bid - kalshi_yes_ask`
`edge_buy_poly_yes_sell_kalshi`	`kalshi_yes_bid - poly_best_ask`
`best_edge`	The larger of the two, gross of fees
`similarity`	0 to 1 confidence that the two questions are the same
`days_apart`	Difference between the two resolution dates
`poly_volume_24h`, `poly_liquidity`, `kalshi_volume_24h`, `kalshi_open_interest`	Activity on each side

Sample rows (real, September 2026):

Polymarket	Kalshi	Poly YES	Kalshi YES	Sim
Will Josh Shapiro win the 2028 Democratic nomination?	2028 Democratic presidential nominee :: Josh Shapiro	0.065	0.048	1.00
Will the price of Bitcoin be above $76,000 on September 11?	BTC price on Sep 11, 2026 at 5pm EDT? :: $76,000 or above	0.887	0.870	0.59
Will 1 Fed rate cut happen in 2026?	Number of rate cuts in 2026? :: Exactly 1 cut	0.057	0.080	0.55

How matching works

Pull the top N active Polymarket Yes/No markets by 24h volume, and every open Kalshi market (parlay combinations excluded).
Tokenise both questions (synonyms folded: BTC = Bitcoin, GOP = Republican, and so on) and score token overlap. Matching numbers (strikes, years) add confidence; conflicting numbers halve it.
Reject pairs whose market type differs (a spread is not a moneyline, an exact score is not an over/under), whose Kalshi leg is not named in the Polymarket question, whose negation differs, or whose resolution dates are more than Max days apart.
Keep the best Kalshi match per Polymarket market above Min similarity.

Rows are sorted by similarity, then edge. A large edge on a low-similarity row is almost always a different question, not free money. Similarity 1.0 means the same wording; 0.55 to 0.7 means read both rule sets before you act.

Input

Option	Default	What it does
Polymarket markets to scan	300	Top N by 24h volume
Min Polymarket 24h volume	1000	Ignore thin markets
Min similarity	0.5	Raise to 0.7 for strict matches only
Max days between end dates	7	Different windows are different markets
Kalshi category	any	Restrict to Politics, Economics, Crypto, Sports, and so on
Only pairs with positive edge	off	Output only rows where `best_edge > 0`
Max pairs	500	Cap output and spend

Pricing

Pay per event: one small charge per matched pair. Scanning is free; you pay only for rows returned. A typical run with defaults returns 20 to 60 pairs in about 30 seconds.

Notes and limits

Edges are gross: they ignore Polymarket and Kalshi fees, spread crossing, slippage and the capital lock-up until resolution. Treat them as a screen, not a signal.
Both venues can word the "same" question with different resolution sources or deadlines. days_apart and the note field are reminders; the rule text is on each venue's page.
Polymarket multi-outcome markets (two teams, several candidates) are skipped; only Yes/No markets are compared.
This Actor never places orders.

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