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

Developers working in research, journalism, and quantitative trading increasingly rely on prediction market datasets. Through PolyGram, the Polymarket platform—the globe's foremost prediction market—offers comprehensive APIs that enable builders to leverage extensive market intelligence and historical data.

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 and highlight markets responding to recent developments and announcements
Aggregators: Benchmark implied probabilities between Polymarket, Kalshi, and Metaculus side-by-side
Alert systems: Trigger notifications whenever a market crosses predetermined volatility or price boundaries
Academic research: Analyse historical settlement records to evaluate prediction accuracy and market efficiency

FAQ

Is the Polymarket API free to use?: Yes — accessing market data via the Gamma API carries no cost, though unauthenticated requests face rate restrictions (approximately 100 per minute). Submitting orders on the CLOB requires an active wallet, yet data retrieval remains complimentary.
Is there a Python library for Polymarket?: Multiple community-developed Python packages are available on GitHub. Look for "polymarket-py" to find the actively maintained versions with the most recent updates.