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Best prediction market APIs for AI agents (2026)
Picked on safety, documentation and honest costs, not payouts. Last checked 2026-10-17.
⚠ Risk note. Prediction markets can go to zero on a single outcome, liquidity can vanish near resolution, and rules on who may trade differ sharply by country. Polymarket's international site is close-only for US persons (US residents use the separate Polymarket US); Kalshi is a US exchange with limited non-US access. Using a VPN to get around a geoblock breaks the venues' terms and can get funds frozen. Not financial advice.
Our picks
Best for US developers: Kalshi API
Regulated US exchange with a real demo environment (separate keys and mock funds) and documented token-bucket rate limits. Start on demo.
Official Python and TypeScript SDKs with order preview and cancel-all. Needs an ID-verified Polymarket US account.
Best agent framework (outside the US): Polymarket Agents
Polymarket's own MIT framework with RAG and news tools. US persons can't trade with it, and confirm it targets CLOB V2 before trading.
The only official prediction market trading MCP we found, with a human approving each order in chat. No testnet.
Play money, bots explicitly allowed, 500 requests a minute. Ideal for testing an agent's forecasting before real money.
How we pick
- Official API and clear terms on automated trading.
- A way to test without real money, or an honest note when there isn't one.
- Region rules stated up front.
Comparison
| Tool | Live / paper | Pricing | Regions | Visit |
|---|
| Kalshi API | live; separate demo environment with mock funds (demo.kalshi.co) | API access free; exchange trading fees apply per contract | US: yes (CFTC-regulated exchange); some contracts may be restricted in some states. Non-US access is limited: check Kalshi's eligibility page for your country. | Visit Kalshi API |
|---|
| Polymarket API | live only (no testnet); CLOB V2 since Apr 28 2026 | API access free; trading fees vary by market | International polymarket.com: US persons cannot open positions (US is close-only) and other jurisdictions are blocked. US residents: use Polymarket US (separate CFTC-regulated app, ID-verified, separate API). | Visit Polymarket API |
|---|
| Polymarket Agents | live (trades via the Polymarket API) | free, open source | Polymarket's terms bar US persons and other restricted jurisdictions from trading through the international API, including via agents. | Visit Polymarket Agents |
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| Polymarket US API | live | API access free; trading fees per Polymarket US schedule | US residents only, via the Polymarket US iOS app with identity verification. | Visit Polymarket US API |
|---|
| Limitless Exchange | live only; no sandbox or testnet (docs say rehearse with minimum-size live orders) | API access free; trading fees per market | Check Limitless's terms for restricted jurisdictions before trading. | Visit Limitless Exchange |
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| Manifold Markets API | play money (mana); no real-money risk | free | Available globally (play money). | Visit Manifold Markets API |
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| Kalshi MCP Server (community) | demo and live; trading off by default | free, open source | Same eligibility as Kalshi. | Visit Kalshi MCP Server (community) |
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| Prediction.Markets API | data only (no execution) | free during beta (1,000 req/day); paid tiers announced | Data viewable globally. | Visit Prediction.Markets API |
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FAQ
Can US residents trade Polymarket with an API or agent?
Not on the international polymarket.com: the US is close-only there, and Polymarket's own Agents repo says US persons may not trade through the API or agents. US residents can use Polymarket US, a separate CFTC-regulated app with its own ID-verified accounts and API.
Is Kalshi available outside the US?
Kalshi is a CFTC-regulated US exchange. Non-US access is limited and changes; check Kalshi's eligibility page before building on it.
Which prediction markets have a sandbox?
Kalshi has a full demo environment with mock funds. Manifold uses play money, so it is a safe place to test agent logic. Polymarket and Limitless have no testnet; their docs suggest minimum-size live orders.
Is there an official prediction market MCP?
Limitless runs an official trading MCP at api.limitless.exchange/mcp. Kalshi and Polymarket have community MCP servers only, as of October 2026.
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