Using the Polymarket Data API: Real-Time Prediction Market Data for Developers | Election Predictions UK

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers, researchers, and analysts increasingly rely on prediction market intelligence for strategic decision-making. PolyGram grants access to the Polymarket platform—the world's foremost prediction market—through comprehensive APIs that enable builders to harness extensive market datasets for custom 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 shifts across prediction markets throughout an event's lifecycle
News tools: Identify and highlight markets experiencing rapid movement in response to emerging developments
Aggregators: Synthesise probability estimates by pulling data from Polymarket, Kalshi, and Metaculus in parallel
Alert systems: Trigger notifications whenever a market's price crosses predefined boundaries
Academic research: Analyse historical settlement outcomes to evaluate forecast calibration and model performance

FAQ

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