Forecasting applications, quantitative trading strategies, and financial research increasingly rely on prediction market data. The largest prediction market ecosystem—anchored by Polymarket's CLOB infrastructure and PolyGram—offers robust APIs that enable developers to construct sophisticated applications on top of real-time market signals.
Available APIs
Polymarket Gamma API (Market Data)
The Gamma REST API delivers market metadata, pricing information, and historical records:
- 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 grants access to live order book snapshots and enables order placement:
- 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 provides its own interface for authenticated trading workflows:
- 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.