Using the Polymarket Data API: Real-Time Prediction Market Data for Developers

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers, researchers, and analysts increasingly rely on prediction market intelligence for strategic decision-making. PolyGram grants access to the Polymarket platform—the world's leading prediction market—through comprehensive APIs that unlock detailed market datasets for custom applications and analytical workflows.

Available Data Endpoints

Gamma API (Market Data)

GET https://gamma-api.polymarket.com/events
  ?limit=100&active=true&order=volume24hr
  Returns: event metadata, current prices, volume, tags

GET https://gamma-api.polymarket.com/events/{slug}
  Returns: full event with all markets, prices, descriptions

GET https://gamma-api.polymarket.com/markets/{conditionId}
  Returns: single market details, current order book price

CLOB API (Order Book)

GET https://clob.polymarket.com/book
  ?token_id={tokenId}
  Returns: full order book depth (bids/asks)

GET https://clob.polymarket.com/prices/history
  ?market={conditionId}&resolution=1h&startTs=1700000000
  Returns: hourly price history

WebSocket: wss://ws-subscriptions-clob.polymarket.com
  Subscribe to real-time price updates

Python Quickstart

import requests

# Get top prediction markets by volume
r = requests.get(
    "https://gamma-api.polymarket.com/events",
    params={"limit": 10, "active": "true", "order": "volume24hr"}
)
for event in r.json():
    market = event["markets"][0] if event.get("markets") else {}
    prices = market.get("outcomePrices", "[0.5,0.5]")
    import json; p = json.loads(prices)
    print(f"{event['title'][:50]}: YES={float(p[0]):.2%}")

Use Cases

Research dashboards: Monitor probability shifts across time horizons for key events and outcomes
News tools: Identify and highlight markets responding to current developments
Aggregators: Synthesise probability estimates by combining Polymarket, Kalshi, and Metaculus signals
Alert systems: Trigger notifications whenever a market crosses predefined volatility or price boundaries
Academic research: Leverage resolved market records to evaluate election forecasting methodologies and prediction accuracy

FAQ

Is the Polymarket API free to use?: Absolutely — the Gamma API (market data) carries no cost, though unauthenticated requests face rate restrictions (roughly 100 per minute). The CLOB API permits free data retrieval; placing orders requires an active wallet.
Is there a Python library for Polymarket?: Community developers have published several Python packages on GitHub. Look for "polymarket-py" repositories to find the most actively maintained implementations.