Methodology

Platform research

Platform profiles are compiled from primary sources: the platforms' own documentation, published fee schedules, regulatory filings and announcements from bodies such as the CFTC, and reputable financial press. Each profile covers the same dimensions — regulation, settlement currency, custody, fees, funding methods, market coverage and liquidity — so platforms can be compared like for like.

Facts such as fee schedules and eligibility rules change. We record the review date on comparison pages, state figures as "indicative", and link to the platform as the authoritative source. If you spot something out of date, we want to know: hello@predictionmarketcompare.com.

Demonstration data

All market prices on this site are demonstration data. Version 1 does not connect to platform APIs. The example markets, prices, volumes and spreads exist to illustrate how cross-platform comparison will work; they are labeled as demonstration data wherever they appear and must not be used for trading decisions. When live integrations ship, this section will be replaced by documentation of data sources, refresh frequency and known gaps.

Matching equivalent markets

Comparing prices across platforms only makes sense when contracts truly resolve on the same outcome. Two markets that sound identical can differ in resolution source, deadline or edge-case handling — differences that legitimately justify different prices. Our matching standard, which live data will inherit, is: same underlying event, compatible resolution criteria, same timeframe. Markets that fail any of these tests are not presented as equivalent.

Fees

We describe fees structurally rather than reducing them to a single number, because platforms charge in different ways: Kalshi uses a formula-based per-contract fee that varies with price, while Polymarket has historically charged no trading fee but involves funding costs around USDC. Where we characterize one platform as cheaper, we say for whom and under what conditions.

Liquidity

Liquidity assessments consider typical order-book depth on flagship markets, bid-ask spreads, and how depth falls off across the long tail. In version 1 these are qualitative judgments based on observation and public volume data; with live data they will become measured quantities with stated definitions.

Editorial ratings

The 0–5 ratings on the compare page are editorial opinions summarizing the dimensions above: liquidity and depth, fees and total cost, ease of use, and regulatory footing. They are not derived from a formula, and they are never influenced by commercial relationships — we currently have none with any platform.

Corrections

When we get something wrong, we fix the page and update its review date. Material errors — anything that could meaningfully mislead a reader's platform choice — are noted on the corrected page.