Polymarket vs Kalshi — for bot developers
Comparison of Polymarket and Kalshi from a programmatic-trading perspective: API access, fees, markets, settlement, jurisdiction.
At a glance
| Feature | Polymarket | Kalshi |
|---|---|---|
| Jurisdiction | Polygon, non-US-restricted | US-regulated (CFTC) |
| API | Public CLOB + Gamma + Data APIs | REST API, account-gated |
| Fees | Maker rebates, taker fee curve | Per-contract fees |
| Markets | Crypto, sports, politics, weather, more | Politics, economics, weather, sports |
| Settlement | Chainlink RTDS (crypto) / committee | CFTC-supervised |
| Minimum bet | ~$5 (min shares × price) | Varies by contract |
| Auth | Wallet signature (Polygon) | Account API key |
Detail by axis
API access
Polymarket offers three separate APIs: the CLOB for order placement, the Gamma API for market discovery, and the Data API for fills and positions. All are public and require only a wallet signature for authenticated endpoints. Kalshi's API requires an account with a verified US identity and uses an API key.
Fees
Polymarket charges takers a non-linear fee that peaks near p=0.50. The maker side earns rebates, making it attractive for resting orders. Kalshi uses a simpler per-contract model; rates vary by market category.
Market variety
Polymarket has a wider and more experimental market catalog. Kalshi focuses on regulated categories with higher credibility for US bettors.
Settlement
Polymarket uses Chainlink RTDS for short-duration crypto binaries and a resolution committee for other markets. Kalshi is CFTC-regulated with formal settlement procedures.
Which should I choose?
If you are outside the US and want maximum market variety with a maker-rebate model: Polymarket. If you are in the US and want regulated, USD-settled markets: Kalshi. Most predtools bots target Polymarket today; Kalshi support is on the roadmap.