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 information for building tools, conducting studies, and understanding market sentiment. PolyGram provides access to Polymarket's comprehensive API infrastructure, unlocking the full depth of the world's most active prediction market dataset.

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 specific outcomes and events in real time
News tools: Identify and highlight markets responding to emerging developments
Aggregators: Synthesise forecast data from Polymarket, Kalshi, and Metaculus side by side
Alert systems: Trigger notifications whenever market movements exceed predefined boundaries
Academic research: Leverage resolved market records to evaluate prediction quality and forecast performance

FAQ

Is the Polymarket API free to use?: Yes — market data via the Gamma API carries no charge, subject to rate restrictions (approximately 100 requests per minute without authentication). Submitting orders on the CLOB requires an active wallet, though retrieving data remains complimentary.
Is there a Python library for Polymarket?: Community developers have published several Python packages on GitHub. Look for "polymarket-py" to discover the most actively maintained implementations.