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

Developers, researchers, and analysts increasingly rely on prediction market information for strategic decision-making and empirical studies. PolyGram provides access to Polymarket's comprehensive API infrastructure, enabling builders to leverage the globe's most substantial prediction market dataset through programmatic interfaces.

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 how prediction market odds shift throughout the lifecycle of a given event
News tools: Identify markets experiencing rapid movement in response to emerging developments
Aggregators: Examine probability divergence across Polymarket, Kalshi, and Metaculus platforms
Alert systems: Trigger notifications whenever a market experiences significant price swings
Academic research: Utilise resolved market outcomes to evaluate prediction accuracy and forecaster performance

FAQ

Is the Polymarket API free to use?: Absolutely — accessing market data through the Gamma API incurs no cost, though unauthenticated requests face rate restrictions (approximately 100 per minute). Submitting orders via the CLOB requires wallet funding, though querying order book information remains complimentary.
Is there a Python library for Polymarket?: Multiple community-developed Python libraries are available on GitHub. Look for "polymarket-py" to discover the most actively maintained versions.