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

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers, researchers, and analysts increasingly rely on prediction market data for insights into collective forecasting. PolyGram provides access to the Polymarket platform—the world's most active prediction market—through comprehensive APIs that enable custom applications 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 how probabilities shift across events over time within prediction markets
News tools: Identify markets experiencing significant movement following major announcements
Aggregators: Synthesise probability estimates from Polymarket, Kalshi, and Metaculus into unified views
Alert systems: Trigger notifications whenever a market's price crosses predetermined boundaries
Academic research: Leverage resolved market outcomes to evaluate forecast quality and model performance

FAQ

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