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 analysts increasingly rely on prediction market information for research, journalism, and quantitative strategy. PolyGram grants access to the Polymarket platform, which operates the globe's most comprehensive prediction market dataset through a suite of developer-friendly APIs.

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 within prediction markets throughout the lifecycle of an event
News tools: Identify and highlight markets responding to emerging developments
Aggregators: Benchmark odds and probabilities between Polymarket, Kalshi, and Metaculus platforms
Alert systems: Dispatch notifications whenever market movement exceeds predetermined boundaries
Academic research: Leverage resolved market data to evaluate forecast performance and prediction accuracy

FAQ

Is the Polymarket API free to use?: Yes — accessing market data via the Gamma API carries no cost and operates under standard rate limits (approximately 100 requests per minute without authentication). Submitting orders through the CLOB requires a wallet with funds, though querying order book 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 the most actively maintained implementations.