What is the best alternative to Polymarket?

Kalshi is the closest. It is a CFTC-designated contract market with a documented trading API and a broad market catalogue, so it covers most of what Polymarket does. PredictIt is older but has no trading API and caps positions, so it is a weaker substitute.

Can I do arbitrage without Polymarket?

Cross-platform arbitrage needs two venues that list the same event and both allow programmatic trading. Kalshi and Polymarket are the pair with the deepest overlap. Replacing Polymarket with a venue that has little overlap or no API leaves the strategy with nothing to trade.

Is it better to replace Polymarket or use it alongside another platform?

For arbitrage, alongside. The edge comes from the price gap between two venues, so dropping one removes the strategy rather than improving it. For directional trading, a single platform is fine and the choice comes down to access, fees and the markets you care about.

Polymarket Alternatives (2026)

The closest alternative to Polymarket is Kalshi: a CFTC-designated exchange with a documented trading API and a market catalogue that overlaps heavily with Polymarket's. PredictIt is the other long-standing name, but it has no trading API and caps how much you can hold in a contract. A handful of newer venues exist too, and for each of them the honest answer is that you should check regulation, API access, fees and overlap yourself before relying on it.

One thing changes the question if you are here for arbitrage: you usually should not be looking for something to replace Polymarket. The strategy needs two venues, so what you want is the best partner for it.

Why people look for a Polymarket alternative

The reasons are practical, not ideological:

Access. Polymarket is geo-blocked at the IP level in countries where a regulator has moved against it. See which European traders can use which platform.
Regulation. Some traders want a venue under a US federal derivatives regulator rather than a crypto-native one.
Fees. Polymarket's taker fee takes a visible bite out of thin edges. The breakdown is in Polymarket fees explained.
Resolution. Polymarket settles through UMA's optimistic oracle, and some traders prefer a venue that runs its own regulated resolution process.

Kalshi: the closest substitute

Kalshi trades event contracts on a CFTC-designated contract market, the same regulatory category as CME and CBOE. It publishes a REST and WebSocket API for programmatic trading, lists politics, economics, crypto and more, and is open in roughly 140 countries, although its Member Agreement names more than fifty restricted jurisdictions. For a US-based trader it is the natural alternative. For a European it may not be available at all. Both sides of that are covered in the Kalshi vs Polymarket comparison.

PredictIt: older, narrower, no API

PredictIt has run since 2014 under a research exemption rather than as a designated exchange. It caps what a single trader can hold in a contract, takes a cut of profits and of withdrawals, and offers no official trading API. Its catalogue leans toward US politics. It is a fine place for directional views on political races and a poor one for anything automated. The full comparison is in Kalshi vs PredictIt.

Newer venues

Polymarket's own US exchange, SX Bet, Predict.fun and Opinion are among the other names you will see covered by third-party scanners. We scan Polymarket and Kalshi for the Starter signal feed and do not claim these are equivalent to them. Before you rely on any of them, check four things.

A four-question test for any alternative

Can you legally open an account from where you live? Check the venue's own terms, immediately before you fund it.
Is there a documented trading API? Without one you cannot place both legs quickly, and the spread will have moved by the time you finish clicking.
What are the all-in costs? Trading fees, deposit and withdrawal costs, and any cut taken on profit.
How much does its catalogue overlap with the other venue? Overlap, not total market count, is what produces cross-market arbitrage candidates.

Replace or pair: what this means for arbitrage

Arbitrage buys YES on one venue and NO on the other for the same event, so a single working leg is worthless. Swapping Polymarket for a venue with thin overlap does not give you a better version of the strategy, it gives you fewer matched pairs. Kalshi and Polymarket are the pair with the broadest overlap we have measured.

The numbers are modest, and we would rather say so. Net edges are thin, a median of roughly 0.7% per position after fees, with capital held until the contract resolves, at a median of about 100 to 110 days. The live figures are on /proof. The real risks are execution (one leg fills and the other does not) and resolution (the two listings settle differently). See how prediction market arbitrage works for the mechanics.

Where Arbitrage Agent fits

Arbitrage Agent is built for exactly this pair. It matches events across Polymarket and Kalshi with AI matching, validates each pair against the resolution rules, calculates the net edge after both venues' fees, and shows you both legs with the orders to place. Automated execution is still in final testing and rolls out to Operator subscribers first, so today the Starter plan means signals and step-by-step guides, not a bot trading for you. If you already have accounts on both venues, see the plans.

Key terms: Cross-Market Arbitrage · Event Contract · Spread

Polymarket Alternatives in 2026: What Exists and What Works for Arbitrage