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

Developers and researchers increasingly rely on prediction market intelligence for quantitative work, journalistic investigation, and data-driven decision-making. PolyGram provides access to the Polymarket platform—the globe's premier prediction market—through comprehensive APIs that unlock sophisticated datasets for builders and analysts.

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 how prediction market odds shift in response to evolving information on particular outcomes
News tools: Identify markets experiencing rapid movement tied to fresh developments
Aggregators: Benchmark implied probabilities across Polymarket, Kalshi, and Metaculus platforms
Alert systems: Trigger notifications whenever a market crosses predetermined price boundaries
Academic research: Leverage resolved market outcomes to evaluate forecast quality and prediction accuracy

FAQ

Is the Polymarket API free to use?: Absolutely—the Gamma API providing market data is available at no cost subject to standard rate restrictions (roughly 100 requests per minute without authentication). Submitting orders on the CLOB requires wallet funding, though querying price and order book data incurs no charge.
Is there a Python library for Polymarket?: The open-source community has developed several Python packages available on GitHub. Look for "polymarket-py" to locate actively maintained versions.