Guides
How these markets actually work
Sixteen guides, each built around a question the platforms leave unanswered.
Every claim is traced to a document: a published fee schedule, a rulebook, a regulator's filing, or a platform's own help centre. Where nobody has published an answer, the guide says so instead of filling the space.
Regulation
The CFTC told exchanges twice this summer to fix it
Three CFTC actions in seven weeks on event contracts. Two advisories call exchange filings deficient on settlement and incentives.
Developer
Kalshi API: free to read, blocked in the browser
Kalshi's API needs no key to read and answers in under 300ms. Send an Origin header and it returns 403. Browser JS cannot call it.
Fees
Maker vs taker: what a resting order really costs
Polymarket charges makers 0.00, a settled fact. Kalshi's own two documents disagree on whether makers are charged at all.
Markets
Prediction market manipulation: 5 categories, 0 dockets
Five manipulation categories on Kalshi and Polymarket, priced from published fee schedules. Every case our corpus names is unsourced, and we say so.
Developer
Polymarket API: two APIs, and you want Gamma
Polymarket runs two public APIs. Gamma lists markets in 122ms with no key, the CLOB carries the book. Plus the paging trap.
Developer
The Polymarket CLOB: 1,000 markets, one response
Polymarket's CLOB returns 1,000 markets and 1.82MB per call. Minimum order is $15 on 962 of them, maker_base_fee 0 on all 1,000.
Developer
Gamma API: how to collect every Polymarket market
Gamma pages by offset, not page number. Pass page= and it repeats slice one. The recipe, the 300 second cache, the price field.
Developer
Building a prediction market bot: what actually breaks
We built one. It evaluates 4.76 million pairs a cycle and finds 5. Half its first matches were nonsense. Paper log down $28.30.
Fees
Prediction market trading fees: price sets your cost
Prediction market trading fees run 0.7% of stake at an entry of $0.90 and 6.3% at $0.10. The full round trip, priced end to end, from our own log.
Evidence
Staged winning-bet videos: five checks
A win video is a set of arithmetic claims. Five checks against Polymarket and Kalshi's own published fee and referral terms.
Access
Support won't respond: the 5-rung escalation ladder
Only one rung can order money back, and it may not reach the exchange itself. The five escalation routes, with the CFTC's own rules cited.
Liquidity
Prediction markets liquidity: a 10.03% edge, $42 deep
Prediction markets liquidity decides what you can trade. Our scanner logged a 10.03% net edge carrying only $42 of deployable size behind it.
Comparison
Kalshi vs Polymarket vs a sportsbook: two are exchanges
A sportsbook takes the other side and prices its margin into the line. Kalshi and Polymarket match you against another trader and publish the fee.
Custody
Where Does Your Money Actually Sit?
Kalshi holds your cash in a CFTC-segregated account. Polymarket holds nothing. Both are fully collateralised, neither is insured. Sources dated.
Markets
Who makes money on prediction markets: not the takers
Polymarket charges makers zero and takers up to 0.07. Kalshi's own docs disagree on whether makers pay at all. Our own log is at minus $28.30.
Access
Withdrawal holds and KYC: the trigger is verification
Documented withdrawal complaints are identity-verification holds, not payment failures. One ran 13 days. Of 214 BBB complaints, 174 got no reply.
Start with the fee guide. The fee is the one cost that applies to every trade you will ever place, and it is arithmetic rather than judgement.