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 datasets to inform decision-making across multiple domains. PolyGram provides access to the Polymarket platform—the globe's most active prediction market ecosystem—through a suite of robust APIs that enable programmatic interaction with comprehensive market intelligence.

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 market probabilities shift across time horizons for particular outcomes
News tools: Identify markets experiencing rapid movement in response to current events
Aggregators: Analyse probability estimates across multiple platforms including Polymarket, Kalshi, and Metaculus
Alert systems: Trigger notifications whenever a market's price crosses predetermined boundaries
Academic research: Utilise resolved market data to evaluate prediction accuracy and forecasting performance

FAQ

Is the Polymarket API free to use?: Yes — market data queries via the Gamma API are available at no cost, though unauthenticated requests face rate restrictions (approximately 100 per minute). Submitting orders through the CLOB requires wallet funding; however, data retrieval remains complimentary.
Is there a Python library for Polymarket?: Multiple community-built Python packages are available on GitHub. Look for "polymarket-py" to discover actively maintained implementations.