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

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers and analysts increasingly rely on prediction market intelligence for research, reporting, and algorithmic trading strategies. PolyGram grants access to the Polymarket platform—the globe's premier prediction market—through comprehensive APIs that unlock deep datasets for custom applications.

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 prediction markets for particular outcomes over extended periods
News tools: Identify markets experiencing rapid movement following major announcements
Aggregators: Evaluate odds across multiple platforms including Polymarket, Kalshi, and Metaculus
Alert systems: Trigger notifications whenever a market swings past predetermined levels
Academic research: Leverage historical settlement records to evaluate forecast performance and model accuracy

FAQ

Is the Polymarket API free to use?: Absolutely — the Gamma API for market data is available at no cost, though rate restrictions apply (~100 requests per minute without authentication). Submitting orders via CLOB requires an active wallet, though querying market information remains complimentary.
Is there a Python library for Polymarket?: Multiple community-driven Python packages are available on GitHub. Look for "polymarket-py" to discover the most actively maintained implementations.