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 intelligence for strategic insights and data-driven decision-making. PolyGram provides seamless access to Polymarket's comprehensive API infrastructure, enabling builders to leverage the globe's most substantial prediction market dataset through robust, developer-friendly endpoints.

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 throughout their lifecycle
News tools: Identify and highlight markets experiencing significant momentum following major announcements
Aggregators: Synthesise probability estimates by pulling data from Polymarket, Kalshi, and Metaculus simultaneously
Alert systems: Trigger notifications whenever market movements exceed predetermined volatility thresholds
Academic research: Analyse historical settlement records to evaluate forecast performance and model accuracy

FAQ

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