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

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers seeking to leverage forecasting intelligence now have access to comprehensive market data streams. The Polymarket platform, integrated through PolyGram's infrastructure, offers sophisticated APIs that tap into the globe's most active prediction market dataset for research, journalism, and algorithmic trading 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 trajectories across prediction markets for events of interest over extended periods
News tools: Identify and highlight markets experiencing significant movement following major announcements
Aggregators: Benchmark odds divergence between Polymarket, Kalshi, and Metaculus platforms
Alert systems: Trigger notifications whenever market valuations shift beyond predetermined boundaries
Academic research: Analyse resolution outcomes and historical pricing data to evaluate forecasting performance metrics

FAQ

Is the Polymarket API free to use?: Absolutely — accessing market data through the Gamma API incurs no cost, subject to standard rate restrictions (approximately 100 requests per minute without authentication). Submitting orders via the CLOB requires wallet funding, though querying market data remains complimentary.
Is there a Python library for Polymarket?: Community developers have published multiple Python libraries available on GitHub. Look for "polymarket-py" to discover the most actively maintained implementations.