Kalshi vs Polymarket
Kalshi and Polymarket are the two venues everyone building on prediction markets ends up comparing. One is a CFTC-regulated exchange. The other is a wallet-native order book running on Polygon. This page lays out the differences, sourced from each venue's own documentation as of 2026-07-09.
| Feature | Kalshi | Polymarket |
|---|---|---|
| What it is | ||
| Type of product | CFTC-regulated exchange | Wallet-native, on-chain order book (Polygon) |
| Regulatory status | CFTC-regulated (US) | Unregulated internationally; separate CFTC-regulated Polymarket US exists |
| Access | ||
| Available in the US | Yes | No, on the international platform |
| Wallet required to trade | No | Yes, a funded Polygon wallet |
| KYC required | Yes, account-based | No (international) · Yes (Polymarket US) |
| Trading | ||
| Auth to trade | Account + RSA-PSS request signing | Wallet signature (EIP-712) + HMAC + per-order signing |
| Trading fee | $0.02/contract flat, maker and taker | Dynamic taker fee up to ~3.15%; makers free, rebated |
| Developer access | ||
| API cost to query | Free | Free |
| REST API | Yes | Yes |
| WebSocket streaming | Yes, included | Yes, included |
| Rate limits | Volume-tiered (Expert…Prestige) | Published per-endpoint limits |
Source: kalshi.com/fee-schedule + docs.kalshi.com (rate limits, RSA-PSS auth) + docs.polymarket.com/developers/CLOB/introduction + docs.polymarket.com/api-reference/geoblock. Verified 2026-07-09.
Market coverage
Both venues span a wide range: elections, economic releases, and sports on Kalshi; politics, crypto, sports, and culture on Polymarket. The category lists overlap more than either venue's own marketing suggests, and coverage alone rarely settles which one to use.
If you're picking a single venue to trade on directly, the next four sections matter more than category breadth. If you're building something that reads prices from both without picking a side, that's a different problem, and it's what the pitch near the bottom of this page is about.
Fees
Kalshi charges a flat $0.02 per contract, on both the maker and taker side of a trade, published on its own fee schedule. Polymarket's fee sits on the taker only, a dynamic rate that tops out around 3.15% on contracts trading near 50 cents, while makers pay nothing and share in a fee pool instead.
Which is cheaper depends on your fill price and how often you're the one crossing the spread rather than resting an order. A frequent taker near even odds on Polymarket can end up paying more than Kalshi's flat rate; a maker on Polymarket can end up paying nothing at all.
API access + data quality
Reading data from either venue costs nothing. The friction shows up in authentication. Kalshi signs every request with RSA-PSS over the timestamp, method, and path, so you're managing a key pair instead of a static token, and it assigns your rate limit by reviewing trading volume and placing you in a tier from Expert up to Prestige.
Polymarket layers a wallet signature (EIP-712) on top of an HMAC handshake just to authenticate, and every order needs its own separate EIP-712 signature on top of that. Both APIs give you the venue's own order book in real time. Neither one tells you anything about what the other venue is doing with the same game.
US access + regulation status
Kalshi is a CFTC-regulated exchange built for US users from the ground up. Polymarket's original international platform blocks the US outright, along with the UK, France, Germany, Italy, the Netherlands, and Belgium, among others.
A separate entity, Polymarket US, launched in 2026 as a CFTC-regulated, KYC'd platform aimed at the US market, though state-by-state availability wasn't confirmed in Polymarket's own docs as of this writing. If you're US-based and want to trade directly rather than through an intermediary, Kalshi is the more straightforward path today.
Settlement
Price gets most of the attention, but settlement is where the two venues can quietly disagree even after their prices matched perfectly going in. Each venue writes its own market rules independently, and on an edge case like a cancelled game or a technical tie, one venue's rulebook can say something the other's doesn't address at all.
The risk here sits underneath the price, in how each market resolves. It only shows up when someone reads both venues' market text and checks whether they agree.
Common questions
Which one is regulated in the US?+−
Which one charges lower fees?+−
Do I need a crypto wallet for either one?+−
Can the same game show a different price on each venue?+−
Can I use both venues at once?+−
How was this page researched?+−
Reading both venues through one API
Reading both venues at once is a different problem than picking one to trade on, and it's the one dino.markets, our own product, solves. It matches the same market across Kalshi and Polymarket, scores each match with an explicit confidence band, and flags the kind of settlement risk described above automatically, instead of leaving you to read both rulebooks yourself. It's read-only, with no order book of its own. Orders still happen on whichever venue you choose, with your funds or wallet held there.