The Top Prediction Market APIs in 2026

Prediction markets are having a moment. Whether you're building a dashboard, a trading bot, or a research tool, you need reliable API access to market data and execution.

The Individual Exchanges

Polymarket is the volume leader. Its API gives you access to events, markets, order books, and trade history on its Polygon-based CLOB. Free for data; trading requires a wallet and USDC.

Kalshi is the go-to for regulated, real-money markets in the US. CFTC-regulated, with a clean REST API. KYC required for trading, but market data is accessible.

Limitless is the leading prediction market on Base, focused on fast-settling crypto and macro markets. Its REST + WebSocket API supports market data, order books, candles, and trading. Known for same-day markets and rapid settlement, with over $1B traded to date.

Opinion is the third-largest prediction market by volume, built on BNB Chain. It offers a CLOB-based API with a Python SDK (opinion-clob-sdk), covering market data, order books, and trading. Its AI-powered oracle handles market creation and resolution, and it's particularly strong on macro and crypto markets.

The Problem With Using Them Directly

If you've tried integrating more than one of these, you already know the pain. Every platform has its own authentication pattern, data format, and order management flow. Building against two or three of them means maintaining two or three separate integrations.

This is the exact same problem CCXT solved for crypto exchanges — and prediction markets now have an equivalent.

PMXT: The Unified Layer

PMXT is an open-source SDK (Python and TypeScript) that provides a single, consistent interface across Polymarket, Kalshi, and Limitless. One data model. One set of method calls. Multiple exchanges.

The data model is clean: Event → Market → Outcome. Search for an event, drill into a market, and interact with outcomes — regardless of which exchange you're on.

import pmxt

api = pmxt.Polymarket() # or .Kalshi()/.Limitless()/.Opinion()/etc.
markets = api.fetch_markets(query="Fed rates")
print(markets[0].title)

import pmxt

api = pmxt.Polymarket() # or .Kalshi()/.Limitless()/.Opinion()/etc.
markets = api.fetch_markets(query="Fed rates")
print(markets[0].title)

Swap Polymarket() for Kalshi() or Limitless() and the code stays the same.

What sets PMXT apart from data-only aggregators is that it supports actual trade execution — limit orders, balance checks, open order management — directly into each venue's order book.

It also covers the full data stack: candles, order books, trade history, and real-time price streaming.

Which Should You Use?

It depends on what you're building:

• Single-exchange data or trading → Use that exchange's native API directly.
• Multi-exchange anything → Start with PMXT. The abstraction pays for itself immediately.
• Regulated US markets only → Kalshi's API, or Kalshi through PMXT.

The prediction market API ecosystem is still young, but it's maturing fast. If you're building in this space, the tooling has never been better.

Links:

PMXT on GitHub · pmxt.dev · Polymarket API · Kalshi API · Limitless API · Opinion SDK