Forecasting applications, quantitative trading strategies, and financial research increasingly depend on prediction market data streams. The largest prediction market ecosystem—anchored by Polymarket's CLOB infrastructure and PolyGram—offers robust APIs that enable developers to construct sophisticated applications atop real-time market signals.
Available APIs
Polymarket Gamma API (Market Data)
The Gamma REST API delivers historical data, current pricing, and event metadata:
- Base URL: https://gamma-api.polymarket.com
- Endpoints: /events, /markets, /positions, /activity
- Authentication: Not required for accessing public market information
- Rate limits: Approximately 100 calls per minute when using unauthenticated access
Polymarket CLOB API (Order Book & Trading)
Real-time order book information and trade execution are available through the CLOB API:
- Base URL: https://clob.polymarket.com
- Endpoints: /book, /trades, /orders, /prices/history
- WebSocket: wss://ws-subscriptions-clob.polymarket.com enables live market updates
- Authentication: Order placement requires ECDSA-signed request authentication
PolyGram API
Authenticated trading workflows and portfolio management are supported via PolyGram's dedicated API:
- Complete reference materials available at PolyGram API Docs
- REST endpoints supporting market discovery, position entry, and account information retrieval
- API key-based authentication for automated trading workflows
Common Developer Use Cases
- Algorithmic trading: Systematic position adjustments triggered by proprietary data feeds
- Research dashboards: Longitudinal probability analysis for political events or macroeconomic outcomes
- Market aggregators: Cross-platform odds comparison across Polymarket, Kalshi, Betfair, and Smarkets
- Embedded widgets: Integrate live odds displays into editorial content or third-party websites
- Alert systems: Trigger notifications when market movements exceed specified parameters
Getting Started: Fetch Market Data
Here is a straightforward Python snippet to retrieve active 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?
- Market data endpoints (Gamma API) are available at no cost subject to rate restrictions. Trading operations (CLOB API) require wallet funding and ECDSA signing but incur no separate API charges.
- Can I paper trade with the API before risking real USDC?
- Polymarket lacks a test environment for risk-free experimentation. Developers often prototype using Manifold Markets API before deploying to Polymarket/PolyGram CLOB for production trading.
- Are there Python or JavaScript SDKs available?
- Community contributors have published unofficial Python and JavaScript libraries for Polymarket integration. Look for "polymarket-py" and "polymarket-js" repositories on GitHub to find actively maintained versions.