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

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers and researchers increasingly rely on prediction market data for quantitative modelling, investigative reporting, and strategic insight. The Polymarket platform, accessible through PolyGram, offers comprehensive APIs that grant access to the globe's most extensive collection of prediction market information.

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 political outcomes and other events in real time
News tools: Identify markets responding to fresh developments and breaking stories
Aggregators: Benchmark Polymarket odds against competing platforms such as Kalshi and Metaculus
Alert systems: Trigger notifications whenever a market crosses predetermined price boundaries
Academic research: Leverage settled market data to evaluate forecast calibration and prediction accuracy

FAQ

Is the Polymarket API free to use?: Absolutely — the Gamma API for market data carries no cost, though unauthenticated requests face rate restrictions (roughly 100 per minute). Submitting orders via CLOB requires an active wallet, though reading data remains complimentary.
Is there a Python library for Polymarket?: Multiple community-built Python packages are available on GitHub. Look for "polymarket-py" to discover the most actively maintained implementations.