Kalshi vs Polymarket
Kalshi vs Polymarket comes down to regulation and access: Kalshi is a CFTC-regulated US exchange that trades in dollars, while Polymarket's international exchange settles on the Polygon blockchain and is close-only for US users. Polymarket US is a separate CFTC-designated exchange.
On fees they are closer than most people think. Both charge takers a fee proportional to p × (1 − p), so fees peak at 50¢ and shrink toward 1¢ and 99¢. At 50¢ for 100 contracts, Kalshi's general fee is $1.75; Polymarket's runs from $0 (geopolitics) to $1.75 (crypto). Both offer free public market data APIs. The table below uses only the official pages cited.
Last updated .
Side by side
| Kalshi | Polymarket (international) | |
|---|---|---|
| Regulation | CFTC-regulated Designated Contract Market (Kalshi Help: How is Kalshi regulated? ↗) | Non-custodial, settles on Polygon; US is close-only (Polymarket: Geographic restrictions ↗). Polymarket US is a separate CFTC-designated exchange (CFTC: QCX LLC d/b/a Polymarket US (DCM filing) ↗) |
| Collateral | US dollars | pUSD, a USDC-backed token on Polygon (Polymarket 101 ↗) |
| Taker fee | round up(M × 0.07 × C × P × (1 − P)); M = 1 on most markets | C × feeRate × p × (1 − p); feeRate 0 to 0.07 by category |
| Fee at 50¢, 100 contracts | $1.75 (most markets) | $1.75 crypto · $1.25 sports · $1.00 politics · $0 geopolitics |
| Maker fee | None on most markets; some series charge maker fees | None; makers can earn rebates |
| API | REST + WebSocket Trade API; public market data without a key; demo environment | Gamma, CLOB and Data REST APIs + WebSockets; public data without credentials |
| Official SDKs | Python (sync, async), TypeScript | Python, TypeScript (Rust in development) |
Volume
We only quote volume from a source we can cite. For Kalshi, the Becker Kalshi dataset counts 7,682,445 markets and 72,134,741 trades through Nov 2025 (State of Kalshi). We don't publish a Polymarket volume figure here.
Sources
- Kalshi Help: How is Kalshi regulated? ↗
- Kalshi fee schedule (PDF) ↗
- Kalshi API docs ↗
- Kalshi SDKs ↗
- Polymarket 101 ↗
- Polymarket: Fees ↗
- Polymarket: Geographic restrictions ↗
- Polymarket: API overview ↗
- CFTC: QCX LLC d/b/a Polymarket US (DCM filing) ↗
Checked Oct 17, 2026. Rules and fees change; check the official page before you rely on them.
Listed projects compared (19)
From this directory. GitHub stars and update dates as of Oct 23, 2026.
| Project | Platforms | Tools | Difficulty | GitHub stars | Repo updated |
|---|---|---|---|---|---|
| Prediction market analysis framework and dataset | Kalshi & Polymarket | Python, Parquet | intermediate | 3,874 | Oct 9, 2026 |
| CloddsBot autonomous trading agent | Kalshi & Polymarket | TypeScript, LLMs | advanced | 2,969 | Oct 2, 2026 |
| PMXT: 'CCXT for prediction markets' | Kalshi & Polymarket | TypeScript | intermediate | 2,170 | Sep 30, 2026 |
| Weather temperature market bot | Kalshi & Polymarket | Python, weather forecasts | intermediate | 780 | Mar 2, 2026 |
| Awesome Prediction Market Tools list | Kalshi & Polymarket | list | beginner | 771 | Oct 7, 2026 |
| Rust copy-trading toolkit | Kalshi & Polymarket | Rust | intermediate | 480 | Sep 7, 2026 |
| Rust Polymarket–Kalshi arbitrage engine | Kalshi & Polymarket | Rust | advanced | 445 | Dec 21, 2025 |
| Cross-venue arbitrage scanner | Kalshi & Polymarket | Python | advanced | 289 | Dec 9, 2025 |
| BTC hourly arbitrage detector | Kalshi & Polymarket | Python | advanced | 254 | May 9, 2026 |
| Polymarket–Kalshi synthetic arbitrage bot (pmxt) | Kalshi & Polymarket | JavaScript, pmxt | intermediate | 187 | Jan 16, 2026 |
| Cross-platform sports arbitrage bot | Kalshi & Polymarket | Rust | advanced | 143 | Jan 18, 2026 |
| Kalshibot for 15-minute Bitcoin markets | Kalshi & Polymarket | JavaScript, Kalshi API, Polymarket CLOB | advanced | 28 | Sep 25, 2026 |
| Real-time tick visualizer | Kalshi & Polymarket | Python, WebSockets | intermediate | 21 | Sep 22, 2025 |
| Event-driven backtest engine for binary prediction markets | Kalshi & Polymarket | Python, Streamlit, Parquet | intermediate | 0 | May 17, 2026 |
| Taker fee calculator for Kalshi, Polymarket and Polymarket US | Kalshi & Polymarket | JavaScript, Node.js | beginner | 0 | Oct 17, 2026 |
| ABT: Kalshi and Polymarket arbitrage review tool | Kalshi & Polymarket | Python, FastAPI, Kalshi API, Polymarket API | intermediate | 0 | Oct 20, 2026 |
| Do prediction markets know what the Fed will do? Kalshi and Polymarket vs futures study | Kalshi & Polymarket | Python, Kalshi API, Polymarket data, futures and FX tick data | advanced | 0 | Oct 21, 2026 |
| Are prediction markets calibrated? Kalshi and Polymarket calibration and favourite-longshot study | Kalshi & Polymarket | Python, pandas, Kalshi API, Polymarket API | intermediate | 0 | Oct 22, 2026 |
| NullOne: Kalshi and Polymarket bot for the EIA natural gas storage report | Kalshi & Polymarket | Python, EIA WNGSR JSON/CSV feeds, Kalshi API, Polymarket API, YAML specs | advanced | 0 | Oct 23, 2026 |
FAQ
Is Kalshi or Polymarket cheaper?
It depends on the market. Both use a p × (1 − p) taker fee. Kalshi's general rate is 0.07; Polymarket's rate is 0 to 0.07 by category, so politics, sports and geopolitics are cheaper on Polymarket at the same price.
Is Polymarket legal in the US?
Polymarket's docs list the United States as close-only on its international exchange. Polymarket US, run by QCX LLC, is a CFTC-designated contract market.
Is Kalshi regulated?
Yes. Kalshi says it is regulated by the CFTC as a Designated Contract Market.
Which has the better API for bots?
Both offer free public market data and official Python and TypeScript SDKs. Kalshi adds a demo environment; Polymarket trading needs a wallet signature plus API credentials.
Are there tools that work with both?
Yes. 19 listed projects support both venues; see the table above.
Not financial advice. Listing is not an endorsement, and we have not checked any profit claims. Read the code before you give any tool an API key or wallet key.
Related: Kalshi trading bots · Polymarket trading bots · Arbitrage bots · Kalshi alternatives · Polymarket alternatives · Prediction market APIs · All 66 projects
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