Prediction Market APIs for Developers: Build with Live Market Data

Forecasting applications, quantitative trading strategies, and financial research increasingly depend on prediction market datasets. The Polymarket CLOB and PolyGram ecosystem offer robust APIs that developers can leverage to construct applications atop the world's foremost prediction market infrastructure.

Available APIs

Polymarket Gamma API (Market Data)

Market metadata, current pricing, and historical records are accessible through the Gamma REST API:

Base URL: https://gamma-api.polymarket.com
Endpoints: /events, /markets, /positions, /activity
Authentication: Public market data requires no authentication
Rate limits: Unauthenticated requests are throttled at approximately 100 per minute

Polymarket CLOB API (Order Book & Trading)

Real-time order book information and trade execution are facilitated through the CLOB API:

Base URL: https://clob.polymarket.com
Endpoints: /book, /trades, /orders, /prices/history
WebSocket: wss://ws-subscriptions-clob.polymarket.com delivers live data streams
Authentication: Order placement demands ECDSA-signed request payloads

PolyGram API

PolyGram's proprietary API enables authenticated trading and account management:

Comprehensive guidance available at PolyGram API Docs
REST endpoints supporting order execution, account holdings, and market discovery
API key-based authentication for automated trading workflows

Common Developer Use Cases

Algorithmic trading: Systematic position adjustment driven by external data sources
Research dashboards: Long-term probability monitoring for political or macroeconomic events
Market aggregators: Cross-platform odds comparison and divergence analysis
Embedded widgets: Integrate live forecast odds into editorial or informational websites
Alert systems: Trigger notifications upon significant market movements

Getting Started: Fetch Market Data

Here is a straightforward Python snippet to retrieve active events in real time:

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?: Market data through the Gamma API carries no cost, though rate restrictions apply. The CLOB API for order submission requires a wallet with sufficient funds and ECDSA signing; transaction fees depend only on network conditions, not API usage.
Can I paper trade with the API before risking real USDC?: Polymarket offers no test or sandbox mode. Consider using Manifold Markets API for risk-free experimentation before deploying capital on the Polymarket or PolyGram CLOB.
Are there Python or JavaScript SDKs available?: Community contributors have built third-party Python and JavaScript libraries for Polymarket integration. Check GitHub repositories for "polymarket-py" and "polymarket-js" to find actively maintained implementations.