Guide 1 May 2026 2 min read

Prediction Market APIs for Developers: Build with Live Market Data

Prediction market data is increasingly valuable for financial research, quantitative trading, and real-time forecasting applications. PolyGram and its underlying Polymarket CLOB expose comprehensive APIs for developers who want to build on top of the largest prediction market ecosystem.

Available APIs

Polymarket Gamma API (Market Data)

The Gamma REST API provides market metadata, prices, and historical data:

Base URL: https://gamma-api.polymarket.com
Endpoints: /events, /markets, /positions, /activity
Authentication: None required for public market data
Rate limits: ~100 requests/minute for unauthenticated access

Polymarket CLOB API (Order Book & Trading)

The CLOB API provides real-time order book data and order submission:

Base URL: https://clob.polymarket.com
Endpoints: /book, /trades, /orders, /prices/history
WebSocket: wss://ws-subscriptions-clob.polymarket.com for real-time updates
Authentication: ECDSA-signed requests required for order submission

PolyGram API

PolyGram exposes its own API for authenticated trading operations:

See full documentation at PolyGram API Docs
REST endpoints for trade placement, portfolio data, and market browse
API key authentication for programmatic trading

Common Developer Use Cases

Algorithmic trading: Automated position management based on external signals
Research dashboards: Historical probability tracking for election or economic forecasts
Market aggregators: Comparing prediction market prices across platforms
Embedded widgets: Show live prediction market odds on news sites or blogs
Alert systems: Notify when a market moves beyond a threshold

Getting Started: Fetch Market Data

A basic Python example to fetch live events:

import requests
response = requests.get(
    "https://gamma-api.polymarket.com/events",
    params={"limit": 10, "active": "true", "order": "volume24hr"}
)
events = response.json()
for event in events:
    print(event["title"], event["volume"])

FAQ

Is the Polymarket API free to use?: Yes — market data (Gamma API) is free with rate limits. Order submission (CLOB API) requires a funded wallet and ECDSA authentication but has no additional fees.
Can I paper trade with the API before risking real USDC?: Polymarket doesn't have a sandbox environment. Use Manifold Markets API for paper trading, then transition to Polymarket/PolyGram CLOB for live trading.
Are there Python or JavaScript SDKs available?: The community has developed unofficial Python and JS libraries for Polymarket. Search GitHub for "polymarket-py" and "polymarket-js" for the latest maintained options.