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 quantitative work. The Polymarket platform—available through PolyGram—offers comprehensive APIs that grant access to the globe's most extensive prediction market information repository.

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 specific prediction markets throughout their lifecycle
News tools: Identify markets experiencing significant movement in response to emerging developments
Aggregators: Benchmark probability estimates between Polymarket, Kalshi, and Metaculus platforms
Alert systems: Trigger notifications whenever a market experiences movement exceeding predetermined limits
Academic research: Leverage historical settlement information to evaluate forecast performance and model accuracy

FAQ

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