How we test prediction-market platforms

On this page · 5

1. How we test
2. Which platforms we have tested
3. How the ranking is decided
4. Conflict-of-interest policy
5. Spot something off?

Last reviewed: October 9, 2026, by Catie Di Stefano.

Every platform we rank has been opened, funded (about $200 each), traded on and withdrawn from by our editor. Trade counts run from about 10 to 50 per platform. We re-check fees, payment methods and availability against each platform's own pages and date every check.

How we test

1. Sign up and verify. Catie opens a real account on the platform with her own details and goes through identity checks like any new user.
2. Deposit. She funds the account with her own money, about $200 per platform, using a normal payment method.
3. Trade. She places real trades, roughly 10 to 50 per platform depending on what it offers, across the kinds of markets the platform lists.
4. Withdraw. She takes money out and notes how the process works.
5. Read the rules. Fees, payment methods, age limits and state availability are taken from each platform's own help pages and terms, with the date we checked them. Legal status comes from court rulings and regulator sources.

We re-check the published facts when a platform changes its fees, offers or availability. The facts and offers on this site were checked October 3, 2026.

Which platforms we have tested

Catie has tested five platforms this way, listed in our ranking order:

• Kalshi: rated 4.8 out of 5
• Polymarket US: rated 4.7 out of 5
• ProphetX: rated 4.7 out of 5
• OG: rated 4.6 out of 5
• Novig: fifth in our ranking, no rating

Rebet (not available in California and not ranked), Sleeper, Chalkboard and Robinhood are described from published information; we have not tested them.

How the ranking is decided

We rank on five things:

• Regulation and California availability (25%): who regulates the platform and whether California residents can open an account.
• Fees and order fills (25%): trading, deposit and withdrawal fees, and how our test orders were filled.
• Market range and liquidity (20%): how many markets are live and how much trading there is on the main contracts.
• Deposits and withdrawals (15%): which payment methods work and how long the money takes to arrive.
• App quality and support (15%): app stability, the website, and how support answered a test request.

The sign-up offer is shown for each platform but does not count toward the ranking.

The ratings (Kalshi 4.8, Polymarket US 4.7, ProphetX 4.7, OG 4.6) are our editor's judgement on these five criteria. They are editorial judgements, not computed scores; the percentages show how much each criterion counts in that judgement. The reasons are given in each platform's review.

Conflict-of-interest policy

We earn commissions when readers sign up to platforms through links on this site: see our full affiliate disclosure. That is how the site is funded. Specifically:

• No platform pays for its position in our ranking or for its rating.
• The ranking follows the five criteria above, and the sign-up offer does not count toward it.
• We also describe platforms we have no affiliate relationship with, and we say when we have not tested a platform.

See our editorial standards for the full corrections, sourcing, and AI-use policy.

Spot something off?

We publish every correction we make. Email catie@californiapredictionmarkets.com and we'll respond within two business days.