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

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Over the past 24–48 hours, prediction market platforms have continued to demonstrate their value across research, journalism, and quantitative trading. The Polymarket ecosystem, accessible through PolyGram, provides comprehensive APIs enabling developers to leverage the globe's most extensive prediction market dataset 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 significant movement in response to recent developments
Aggregators: Evaluate probability spreads between Polymarket, Kalshi, and Metaculus side-by-side
Alert systems: Send notifications whenever market movements exceed 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 via the Gamma API carries no cost, subject to rate restrictions (approximately 100 requests per minute without authentication). CLOB order placement requires an active wallet, though reading data remains complimentary.
Is there a Python library for Polymarket?: Multiple community-developed Python libraries are available on GitHub. Look for "polymarket-py" to find the most actively maintained versions.