Kalshi API: how it compares to Polymarket for traders
If you searched for "kalshi api" you’re likely comparing prediction-market data and execution options. Kalshi is a centralized, CFTC-regulated exchange offering its own API for market data and order entry. Polymarket is a decentralized CLOB on Polygon using pUSD and UMA for resolution; PolyArb sits on top of Polymarket to find intra-market arbitrage opportunities. This article explains the practical differences and where PolyArb adds value for traders.
What the Kalshi API provides
Kalshi provides a REST and websocket surface for market data and order placement in a regulated environment. Its API is designed for retail and institutional users who need low-latency access to listed event contracts and trade execution under CFTC oversight. Latency, fees, and account onboarding follow centralized-exchange norms, including KYC for US users. For traders, Kalshi is convenient when you need regulated access to event contracts. It’s a different product from decentralized prediction markets: settlement, custody, and the matching engine model differ materially from Polymarket’s on-chain CLOB and CTF token model.
How Polymarket differs from Kalshi
Polymarket runs on Polygon, uses pUSD for settlement, and exposes market data through Gamma, Data, and CLOB APIs and a market WebSocket. Outcomes are ERC-1155 outcome tokens under Gnosis CTF and resolution uses UMA. Gas is sponsored via the Polymarket Relayer; wallet options include MetaMask, Gnosis Safe, and others. This makes Polymarket attractive if you prefer non-custodial exposure and on-chain settlement semantics. Because the mechanics differ, strategies that work on Kalshi don’t map directly to Polymarket. Pricing, tick sizes, and fees follow Polymarket’s rules and the arbitrage taxonomy PolyArb targets is intra-market (buying complete sets on the same market).
Where PolyArb fits in
PolyArb is a paid service that scans Polymarket for intra-market arbitrage opportunities and executes with low latency. For $99/month you get 40ms latency vs ~800ms typical for free bots, Telegram and Discord alerts, a non-custodial architecture, and a $7.62 minimum guaranteed edge per trade. PolyArb focuses on buying complete sets or both binary legs when best-ask sums fall below $1.00 and automates split/merge/redeem flows. No trade is without risk. PolyArb’s approach reduces execution and latency risk, but users still face resolution disputes via UMA, slippage or partial fills, fee changes, settlement timing, and smart-contract risk.
When to use each platform
Use Kalshi if you need a CFTC-regulated venue and centralized custody with its API and product set. Use Polymarket if you want non-custodial markets, on-chain outcome tokens, and the composability of Polygon. Use PolyArb if you’re specifically hunting intra-Polymarket arbitrage and value low-latency execution plus alerting. If you’re evaluating programmatic access, compare API surfaces, latency guarantees, fees, and regulatory constraints before building strategies.
Start capturing Polymarket arbitrage today
Try PolyArb for $99/month — low-latency execution, Telegram + Discord alerts, non-custodial operation, and a $7.62 minimum guaranteed edge per trade.
FAQ
- Does Kalshi offer a public API for automated trading?
- Yes. Kalshi exposes REST and websocket endpoints for market data and order placement under its platform. Access and exact rate limits are set by Kalshi; US users typically require KYC.
- Can PolyArb trade on Kalshi markets?
- No. PolyArb is built for Polymarket intra-market arbitrage and interacts with Polymarket’s APIs and on-chain flows; it does not route orders to Kalshi or other centralized exchanges.
- What risks does on-chain arbitrage have compared to Kalshi?
- On-chain risks include UMA resolution disputes, smart-contract bugs, settlement timing, and geo-restrictions. Centralized platforms add counterparty and custodial risks. Execution and slippage risks exist on both.