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Apps like Kalshi serve different jobs. Some let you trade event contracts with money; others let you submit probability forecasts or trade with play money. Start with the activity you want, then compare the actual product and account requirements.
This comparison checks public documentation as of October 6, 2026. It does not claim hands-on trading tests, account approvals or a measured ranking of platform liquidity. For a checklist to compare two specific offers, use our Kalshi alternatives decision worksheet.
Compare the purpose before the app name
| Product | Activity to investigate | What to verify first |
|---|---|---|
| Polymarket US | Event-contract trading | Account verification, available contract and US fee schedule |
| Polymarket International | International-market trading and data | Location permissions, wallet workflow and market-specific fees |
| Robinhood event contracts | Event contracts through a derivatives account | Account approval, state restrictions and underlying exchange |
| PredictIt | Political-market research and trading | Current agreement, market limits and fee notices |
| Metaculus | Probability forecasting and scored tournaments | Question resolution rules and tournament conditions |
| Manifold | Social predictions with play money | Creator's resolution criteria and meaning of the currency |
Polymarket: distinguish the US and international products
The Polymarket US account guide describes identity verification before funding or trading. This is a separate onboarding process from the international product. Do not interpret an old statement that international access is restricted as proof that no Polymarket US product exists.
Compare the specific contract you want rather than the brand's total market count. A similar headline can conceal a different cutoff, outcome definition or settlement source. The US-status guide explains the product distinction, and our Polymarket fees guide separates the schedules.
International users should check the platform's location restrictions for the actual activity. An ability to read a market page does not establish permission to open a position. Fee assumptions also need checking: the international documentation describes taker fees on certain markets, not universal zero-fee trading.
Robinhood: app access and exchange access are different
Robinhood's official overview describes event contracts offered through Robinhood Derivatives and partnered exchanges. It requires an approved derivatives account and notes state and contract restrictions. A brokerage login alone does not establish access.
If you already use Robinhood, inspect the exact event in the app: which exchange provides it, what opening and closing costs apply, and how settled funds become available. The user interface can be an alternative to Kalshi's interface while the underlying contract may still be supplied by Kalshi. Our Robinhood payout guide covers settlement and withdrawal distinctions.
PredictIt: recheck recent cost notices
For political-market comparisons, check PredictIt's current markets and participant terms. Its September 23, 2026 product notice says deposits and withdrawals are free and the former 5% withdrawal charge is gone. An older comparison quoting that charge is stale.
That notice does not mean every kind of trading cost or limit has disappeared. Read the applicable agreement and market details before transferring funds, then compare the total cost of your planned position.
Metaculus: forecast probabilities without buying a contract
Metaculus is a forecasting platform that scores predictions against outcomes. Its tournament directory includes both prize and no-prize competitions. A competition award is different from buying a tradable contract; check the particular tournament's eligibility and rules.
This is a useful activity to investigate if your goal is to practice forecasting rather than manage a money position. Write down probabilities before results are known, record your reasoning and review performance over a defined sample. Our Brier-score calculator can score your independently assembled binary predictions; it does not replicate Metaculus's tournament scoring.
Manifold: social markets using mana
The Manifold FAQ describes community-created markets and mana, a play-money currency that cannot be converted to cash. A mana balance is not a withdrawable dollar balance.
Read the creator's question and resolution criteria before interpreting the displayed probability. For a personally interesting question, ask whether the condition is observable, who resolves it and how an ambiguous outcome is handled. A familiar market interface does not make its currency or settlement process equivalent to Kalshi's.
Check liquidity at your size
A platform-wide volume number cannot tell you whether your chosen outcome has an executable quote for your order size. Compare bid, ask, available depth and final costs at the same time. If 100 contracts are your intended size, a quote supported by only five contracts is an incomplete comparison.
Use the slippage calculator for a stated order-book scenario and the profit calculator for explicit payout and cost assumptions. Neither proves the venue will fill an order.
Build a shortlist around your own task
For money trading, shortlist products that offer the exact contract and accept your account under current rules. For practice, compare scoring, question quality and resolution transparency. For research, compare public data, timestamps and the ability to preserve sources.
Alphascope supports prediction-market research. Keep research tools, trading venues and forecasting communities separate when deciding where an action actually happens.