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 data for quantitative work and investigative reporting. PolyGram provides access to the Polymarket ecosystem's comprehensive APIs, enabling builders to leverage the globe's most extensive 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 prediction markets for given outcomes over extended periods
News tools: Identify rapidly shifting markets in response to emerging developments
Aggregators: Evaluate odds disparities between Polymarket, Kalshi, and Metaculus platforms
Alert systems: Trigger notifications when market movements exceed predetermined boundaries
Academic research: Utilise resolved market records to evaluate forecast performance and prediction accuracy

FAQ

Is the Polymarket API free to use?: Absolutely — market data via the Gamma API carries no cost and operates under rate restrictions (approximately 100 requests per minute without authentication). Submitting orders on the CLOB requires a wallet with funds, though retrieving data remains complimentary.
Is there a Python library for Polymarket?: Multiple community-developed Python packages are available on GitHub. Look for "polymarket-py" to find the most actively maintained implementations.