There is no universal “best prediction market app.” First distinguish an exchange from a broker and a play-money forecasting environment. Then compare the specific account route and contract you need. This October 8, 2026 update replaces unsupported volume, liquidity, accuracy and growth rankings with official product facts.
The product map
| Product | Important distinction | Primary reference |
|---|---|---|
| Kalshi | Account guidance includes eligible international users, not US-only access | Individual eligibility |
| Polymarket US | Separate regulated US product | CFTC designation record |
| Polymarket International | Separate product; location restrictions differ from US access | International restrictions |
| PredictIt | Conditional no-action framework rather than DCM registration; amended investment cap | CFTC Letter 25-20 |
| Manifold | Mana cannot be converted to cash | Official FAQ |
| ForecastEx | Contracts accessible through qualified FCMs, with retail-investor documentation | Members and key information document |
| Robinhood | Broker access to multiple partnered exchanges; not simply another Kalshi interface | Event-contract overview |
Account approval, physical location and particular contract restrictions remain separate from those product descriptions. This table does not promise access or recommend funding an account.
Compare costs in their actual units
Use the displayed executable price and quantity, then the relevant exchange and broker fees. A percentage of profits, a per-contract fee, a bid/ask spread and a withdrawal charge are different units. Do not compare them as if all were a fixed percentage of stake.
PredictIt’s September 23 fee update removed withdrawal fees while retaining a 10% trading-profit fee. Polymarket’s US and International fee schedules are separate. The earlier 0%-fee Polymarket default, universal 0–2c Kalshi cost and ForecastEx “unpublished institutional pricing” claim are removed.
Compare a contract, not a coverage badge
For the event you need, record the exact outcome definition, resolution source, timing, exceptional-outcome treatment, quote age, available size and weighted acquisition price. A league appearing in a catalog is not proof of deep liquidity for every game. A public API is not proof that its history is complete or suitable for execution replay.
Our sports venue comparison explains those checks. The historical data buyer guide distinguishes source schemas and observed coverage.
What counts as evidence of accuracy
Compare predictions captured before the outcome with a stated outcome population, timestamps, reliability-bin counts and uncertainty. Agreement with ZenHodl’s model is not calibration against actual results. The former claims that venue probabilities are within 2–5%, or that every platform has demonstrated insider exploitation, were not supported by the named evidence and are removed.
A useful app comparison ends with a reproducible task: identify the permitted account route and the market, then inspect its rules, costs and executable data. It does not need invented monthly-volume estimates or a star rating for depth.