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 intelligence for quantitative strategy, investigative reporting, and data-driven insights. The Polymarket platform—integrated through PolyGram—offers comprehensive APIs that grant access to the globe's most liquid prediction market information streams.

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 implied probabilities across time horizons for key events and outcomes
News tools: Identify markets experiencing rapid repricing in response to emerging information
Aggregators: Benchmark Polymarket odds against competing venues such as Kalshi and Metaculus
Alert systems: Trigger notifications when market prices breach predetermined boundaries
Academic research: Leverage settlement records and historical outcomes to evaluate prediction quality and model performance

FAQ

Is the Polymarket API free to use?: Absolutely—market data endpoints (Gamma API) carry no cost under standard rate allowances (approximately 100 requests per minute without authentication). CLOB order placement demands a capitalised account; however, read-only data access remains complimentary.
Is there a Python library for Polymarket?: Multiple community-built Python packages are available on GitHub repositories. Look for "polymarket-py" to locate actively maintained implementations.