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 informed decision-making across finance, policy, and journalism. The Polymarket platform—available through PolyGram's infrastructure—offers comprehensive APIs that grant access to the globe's most substantial prediction market dataset, enabling sophisticated integrations and analytical workflows.

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 responding to emerging developments and significant announcements
Aggregators: Benchmark implied probabilities between Polymarket, Kalshi, and Metaculus platforms
Alert systems: Trigger notifications upon substantial market movements or volatility spikes
Academic research: Analyse historical settlement records and forecast performance metrics for scholarly publications

FAQ

Is the Polymarket API free to use?: Absolutely — market data via the Gamma API carries no cost subject to standard rate restrictions (approximately 100 requests per minute without authentication). CLOB order placement demands an active funded account; however, data retrieval operations remain complimentary.
Is there a Python library for Polymarket?: Multiple community-developed Python packages are available on GitHub. Look for "polymarket-py" repositories to locate actively maintained implementations.