Refreshed every 30 minutes
The same market, priced two ways
We find the events that trade on Polymarket, Kalshi, Robinhood and PredictIt at the same time, confirm they resolve on identical criteria, and lay both prices side by side. When the combined cost dips under $1, that is a live arbitrage: we flag it the moment it opens and leave it on the board so you can see we caught it. We do not trade it. If you want to, the legs are one tap away.
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111 matched events across venues
31 with a live arbitrage right nowWhich party will win the 2026 US Senate election in South Carolina? for Republican
Sports
Polymarket vs PredictIt Arb +239.0%
Cost to lock $1: 30¢Locked profit: 71¢ per $1
Both markets resolve on the winner of the 2026 US Senate election in South Carolina, with one betting on Democrats and the other on Republicans.
Who will win the 2026 Brazilian presidential election? for Flávio Bolsonaro
Sports
Polymarket vs PredictIt Arb +75.3%
Cost to lock $1: 57¢Locked profit: 43¢ per $1
Both markets resolve on Flávio Bolsonaro winning the 2026 Brazilian presidential election.
Will Trump and Putin meet next in China?
Politics
Size $4kResolves Jan 1, 2027Kalshi / Robinhood vs Polymarket Arb +70.9%
Cost to lock $1: 59¢Locked profit: 42¢ per $1
Who will advance in the Brazilian presidential election? Luiz Inácio Lula da Silva
Politics
Resolves Oct 3, 2028PredictIt vs Kalshi / Robinhood Arb +69.5%
Cost to lock $1: 59¢Locked profit: 41¢ per $1
Will Trump recognize Somaliland? :: During Trump's term
Politics
Size $17kResolves Jan 20, 2029Polymarket vs Kalshi / Robinhood Arb +63.7%
Cost to lock $1: 61¢Locked profit: 39¢ per $1
Will Congress override Trump's veto? Will Congress ever override Trump's veto?
Politics
Resolves Jan 20, 2029PredictIt vs Kalshi / Robinhood Arb +31.6%
Cost to lock $1: 76¢Locked profit: 24¢ per $1
French presidential election: who will advance? Will Jean-Luc Mélenchon qualify for the runoff in the 2027 French presidential election?
Politics
Size $522Resolves Apr 17, 2028Polymarket vs Kalshi / Robinhood Arb +22.7%
Cost to lock $1: 82¢Locked profit: 19¢ per $1
2028 Republican Presidential ticket Will Marco Rubio and Donald Trump be the 2028 Republican Presidential ticket?
Politics
Size $5kResolves Nov 14, 2028Kalshi / Robinhood vs Polymarket Arb +20.4%
Cost to lock $1: 83¢Locked profit: 17¢ per $1
Where will Putin and Zelenskyy next meet? Will Putin and Zelenskyy meet next in Switzerland?
Other
Size $5kResolves Jan 7, 2029Polymarket vs Kalshi / Robinhood Arb +16.6%
Cost to lock $1: 86¢Locked profit: 14¢ per $1
Next James Bond film: Actor cast as James Bond Will Jack Lowden be the next James Bond?
Culture
Size $2kResolves Jan 1, 2030Polymarket vs Kalshi / Robinhood Arb +15.0%
Cost to lock $1: 87¢Locked profit: 13¢ per $1
Will Rubio and Vance both announce a run for President before 2028?
Politics
Resolves Dec 31, 2027Kalshi / Robinhood vs PredictIt Arb +13.6%
Cost to lock $1: 88¢Locked profit: 12¢ per $1
Who will be the next White House press secretary in 2026? for Scott Jennings
Other
Resolves Dec 31, 2026Polymarket vs PredictIt Arb +13.4%
Cost to lock $1: 88¢Locked profit: 12¢ per $1
2028 Republican presidential nominee Will Marco Rubio be the nominee for the Presidency for the Republican party?
Politics
Size $4kResolves Nov 7, 2028Polymarket vs Kalshi / Robinhood Arb +12.9%
Cost to lock $1: 89¢Locked profit: 11¢ per $1
Where will Putin and Zelenskyy next meet? Will Putin and Zelenskyy meet next in Hungary?
Other
Size $10kResolves Jan 7, 2029Polymarket vs Kalshi / Robinhood Arb +12.5%
Cost to lock $1: 89¢Locked profit: 11¢ per $1
French presidential election: who will advance? Will Édouard Philippe qualify for the runoff in the 2027 French presidential election?
Politics
Size $266Resolves Apr 17, 2028Polymarket vs Kalshi / Robinhood Arb +11.7%
Cost to lock $1: 90¢Locked profit: 10¢ per $1
Where will Trump and Putin next meet?
Politics
Size $6kResolves Jan 8, 2029Polymarket vs Kalshi / Robinhood Arb +11.1%
Cost to lock $1: 90¢Locked profit: 10¢ per $1
Will Stephen A. Smith announce a run for president before 2028?
Politics
Resolves Nov 7, 2028Polymarket vs PredictIt Arb +8.5%
Cost to lock $1: 92¢Locked profit: 8¢ per $1
2028 Democratic Presidential ticket Will Jon Ossoff and Alexandria Ocasio-Cortez be the 2028 Democratic Presidential ticket?
Other
Size $6kResolves Nov 14, 2028Kalshi / Robinhood vs Polymarket Arb +8.5%
Cost to lock $1: 92¢Locked profit: 8¢ per $1
Will the America Party contest the 2028 U.S. presidential election? Will a party founded by Elon Musk contest the 2028 U.S. presidential election?
Politics
Size $3kResolves Sep 8, 2028Polymarket vs Kalshi / Robinhood Arb +8.2%
Cost to lock $1: 92¢Locked profit: 8¢ per $1
Who will leave Trump's Cabinet next? Will Doug Collins be the next person to leave the Trump Cabinet?
Politics
Resolves Jan 20, 2029Kalshi / Robinhood vs PredictIt Arb +7.5%
Cost to lock $1: 93¢Locked profit: 7¢ per $1
Showing 1 to 20 of 111 results
How we find it
We pull open binary markets from every venue, normalize each to a single YES/NO price (the cost of a $1 payout), and match the same real-world event across venues. An agent confirms both legs resolve on identical criteria before a pair lists, then we refresh prices every 30 minutes and flag the moments a combined cost drops under $1.
Why we do not trade it for you
Real execution carries risk we are not taking on: payout timing differs across venues, capital is locked until resolution, and fees, gas, KYC and withdrawal limits eat into the spread. Live arbs are often fleeting. This is a structured feed, not financial advice. Verify the resolution criteria and fees yourself before trading.
Prediction market arbitrage API and MCP for agents
Every match on this board is also a free JSON API and an MCP tool, so a trading agent can poll live Polymarket, Kalshi and PredictIt arbitrage opportunities and act on them. No API key required.
curl https://www.startuphub.ai/api/v1/arbitrage?arbs_only=1Prediction market arbitrage, explained
- What is prediction market arbitrage?
- When the same event trades on more than one venue (Polymarket, Kalshi/Robinhood, PredictIt), the YES price on one venue and the NO price on another can add up to less than $1. Buying both locks a guaranteed $1 payout for less than $1, and the difference is the arbitrage.
- Is there a Polymarket vs Kalshi arbitrage API?
- Yes. This board is a free JSON API at
/api/v1/arbitrageand an MCP tool (get_arbitrage), so bots and agents can poll live Polymarket, Kalshi and PredictIt arbitrage opportunities without scraping each venue. - Which venues are covered?
- Polymarket, Kalshi (and Robinhood, which trades on Kalshi's exchange), and PredictIt. Every market is normalized to a single YES/NO price and matched to the same real-world event across venues.
- Is it free, and is this financial advice?
- The board and the API are free, no signup. This is an informational feed, not financial advice. Live arbitrages are often fleeting, and fees, KYC, gas and withdrawal limits eat into the spread, so verify each market's resolution rules and costs before trading.
- What are the types of Polymarket arbitrage?
- Two main kinds. Internal (bundle) arbitrage is buying YES and NO inside a single Polymarket market when they sum to under $1 (for example YES at 60¢ and NO at 38¢ totals 98¢, a locked 2¢). Cross-platform arbitrage is the same real-world event priced differently across venues: buy the cheap YES on one and the cheap NO on another (Polymarket vs Kalshi/Robinhood or PredictIt). This board scans the cross-platform kind live.
- Is arbitrage allowed on Polymarket?
- Yes. Buying mispriced YES/NO shares is ordinary market activity, not against Polymarket's rules. The real constraints are practical: order-book depth is thin at the mispriced level, so large size is hard to fill, and Polymarket restricts some jurisdictions (including the US), so check your own eligibility.
- Is Polymarket arbitrage profitable?
- Spreads are usually small (often 1-5%) and short-lived. High-frequency bots capture the obvious ones in milliseconds, and gas, fees, and slight differences in how each venue resolves an event can erase a thin edge. It can be profitable on real, verified mismatches with fast execution, which is exactly what this scanner surfaces, but it is not free money.
- Is there a Polymarket arbitrage scanner or bot?
- This page is a live Polymarket, Kalshi and PredictIt arbitrage scanner, refreshed every 30 minutes. For a bot, point it at the free JSON API (
/api/v1/arbitrage) or theget_arbitrageMCP tool: both return the same matched pairs and live prices, so an agent can poll opportunities and act without scraping each venue.