Kalshi vs Polymarket vs Metaculus vs insiderz

Kalshi is a CFTC regulated US exchange where you trade event contracts with dollars. Polymarket is a crypto exchange, mostly offshore, blocked by order in a growing list of countries. Metaculus is a no money forecasting platform scored on accuracy. insiderz is a no money platform where your call is scored against the live Polymarket price. Money, regulator and what the ranking measures are the three real differences.

Last checked: 4 September 2026.

How do the four compare at a glance?

Every cell was checked on 4 September 2026 against the documents linked in the sources. "CFTC regulated venue" means a designated contract market registered with the US Commodity Futures Trading Commission. "What the public ranking measures" is what the platform actually sorts people by.

Platform	Money at stake	Deposit needed	CFTC regulated venue	Blocked by order in Italy and Spain	What the public ranking measures	Public API
Kalshi	Yes	Yes	Yes	Yes	Not published	Yes
Polymarket	Yes	Yes	Yes, for its US entity only	Yes	Profit and volume	Yes
Metaculus	No	No	No	No	Accuracy scores	Yes
insiderz	No	No	No	No	Beats market, Events, Edge, Early	Yes

Two of the four require money and are blocked by two EU regulators. Two require nothing and are not on either list. That is the split that decides the question for most readers outside the United States.

What is Kalshi?

Kalshi is a prediction market that runs a CFTC regulated exchange, so its event contracts are financial instruments settled in dollars rather than bets placed with a bookmaker. The Congressional Research Service described the structure in its briefing Prediction Markets: Policy Issues for Congress of 20 March 2026.

Kalshi is mostly a sports venue now. The same CRS briefing reports that as of February 2026, roughly 87 percent of Kalshi's 39.7 billion dollars traded in the previous year was on sports.

Its legal position in the United States got stronger in 2026 and is still contested. On 6 April 2026 the Third Circuit decided KalshiEX LLC v. Flaherty, No. 25-1922, holding that sports related event contracts are swaps under the Commodity Exchange Act and that the Act preempts New Jersey gambling law as applied to contracts listed on a CFTC licensed exchange, as summarized by Paul, Weiss. The decision was divided, other states are still litigating, and the CRS notes the CFTC filed an amicus brief against Nevada in February 2026.

Outside the United States it is a different story. Kalshi does not escape European gambling regulators by being a US exchange: kalshi.com appears on the Italian list of inhibited gambling sites updated on 5 August 2026, and Spain's Ministry of Consumer Affairs ordered a precautionary block of Kalshi alongside Polymarket on 26 May 2026.

What is Polymarket?

Polymarket is a crypto based prediction market where you trade yes and no shares priced between 0 and 1, settled in stablecoins. Its scale is comparable to Kalshi's: the CRS briefing of 20 March 2026 puts 36.2 billion dollars traded on Polymarket in the previous year, with sports at 38 percent, the largest single category but far from the whole.

Its structure is unusual and worth understanding before comparing anything else. The CRS describes Polymarket's largest exchange as domiciled offshore, claiming to block US users and therefore not effectively subject to CFTC rules, alongside a smaller CFTC approved exchange it acquired for US customers, which the briefing calls a dual exchange structure.

The cost of that structure is access. Polymarket has collected more blocking orders than any other platform in this comparison: France's Autorité nationale des jeux ordered a block on 17 July 2026, Italy and Spain acted in the same summer, and the Ontario Securities Commission settled with its operators in April 2025 over the province's binary options ban. The country by country picture is in where Polymarket is blocked.

The other thing to know is what its public ranking says about a trader. Polymarket's leaderboard sorts by profit and volume, which rises with the size of the stake rather than with the quality of the forecast. That distinction is the subject of P&L is not skill.

What is Metaculus?

Metaculus is a forecasting platform, not a market. People post probabilities on questions, and when a question resolves the platform scores each forecaster. There is no trading, no order book, no deposit and no stake. The codebase is open source on GitHub under a BSD 2-Clause license.

Its questions are the longest horizon and the most research shaped of the four, which is why researchers use it as a benchmark. The arXiv paper Evaluating LLMs on Real-World Forecasting Against Expert Forecasters, published in August 2025, ran frontier models against 464 Metaculus questions and found they beat the general crowd and lost to expert forecasters.

Money shows up only as prizes. The Bridgewater x Metaculus 2026 competition ran from 12 January to 13 March 2026 with a 30,000 dollar prize pool and free entry. Bots can play through the API, and Metaculus publishes a template bot for its AI forecasting tournament.

The limitation, for the question this page asks, is the benchmark. Metaculus scores you against the community and against a baseline. It does not tell you whether you beat a traded price.

What is insiderz?

insiderz is a no money platform where you make a public call on the same yes or no events Polymarket lists, and the call is scored against the market. A call is yes or no plus how sure you are.

The call is locked the second it is posted. The time and the Polymarket price at that moment are frozen with it, and the call cannot be edited or deleted, not by the person who made it and not by us. When the event resolves, the call is scored against that frozen price, so being right where the market was wrong is what counts. The insiders ranking sorts people on Beats market, Events, Edge and Early.

There is no money in either direction: no deposit, no purchasable currency, no prize pool, no token. Identity is a wallet signature only, in the Sign in with Ethereum pattern, so no email, no password and no name are needed. Calls go public after a delay, and followers can ask an insider for live access to see calls as they are made. Bots play through the public API under the same rules and the same ranking.

Now the part a comparison page usually leaves out. insiderz launched in September 2026, so it has no long accuracy history of its own, no liquidity, no prizes and no money to win. Kalshi and Polymarket have billions of dollars of resolved volume behind their prices, and Metaculus has years of resolved questions. If you want a price to trade, this is the wrong site. If you want the price to be the bar you are measured against, it is the only one of the four that does that.

Which one can you actually use, by country?

Start with where you are, because in most of Europe the choice is made for you.

In Italy and Spain, Kalshi and Polymarket are both subject to blocking orders as of September 2026, and in France the ANJ order of 17 July 2026 covers Polymarket. Metaculus and insiderz appear on none of those lists, because a platform with no stake and no prize falls outside the gambling definitions the orders rely on. In Canada, Ontario residents are barred from Polymarket by the 2025 OSC settlement.

In the United States, all four are usable in some form, with Kalshi the most straightforward because its venue is registered with the CFTC and the Third Circuit ruled in April 2026 that the Commodity Exchange Act preempts state gambling law for contracts listed there. State litigation continues, so that position may move.

This is not legal advice, and access rules change faster than any page can. Check where Polymarket is blocked for the current country table.

Which one fits your goal?

Pick by what you want out of it.

• To trade event contracts in dollars on a US regulated venue: Kalshi.
• To trade the deepest global book on politics, crypto and culture, where the law allows it: Polymarket.
• To build a long horizon, research grade forecasting record: Metaculus.
• To prove you called something the market got wrong, with no deposit and no account beyond a wallet: insiderz.

The four are not substitutes. Kalshi and Polymarket answer "how much can this position make". Metaculus answers "how accurate are you". insiderz answers "did you see it before the price did".

Method: how this comparison was built

Four platforms were chosen because they are the four people compare in the same sentence, and because they cover the two axes that matter: money or no money, and market price or accuracy score.

Every cell in the table is either a public regulatory document, a platform's own public repository, or a peer visible fact that can be checked in a minute. Volumes and their share of sports come from one source, the Congressional Research Service briefing of 20 March 2026, so the two numbers are measured the same way. No number on this page comes from insiderz, because a platform that launched in September 2026 has no accuracy history worth citing yet.

This page is rechecked quarterly and the check date moves only when the cells are verified again. For the no money options in full, including Manifold, Good Judgment Open and Fatebook, see free prediction markets with no money. For the evidence on whether money makes forecasts better, see play money versus real money.