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

Developers, researchers, and analysts increasingly rely on prediction market datasets for insight and quantitative work. PolyGram grants access to the Polymarket platform—the globe's foremost prediction market—through comprehensive APIs that enable custom applications and integrations atop its extensive data infrastructure.

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 prediction market odds shift throughout the lifecycle of an event
News tools: Identify markets experiencing rapid movement in response to fresh developments
Aggregators: Benchmark odds across Polymarket, Kalshi, and Metaculus platforms side-by-side
Alert systems: Trigger notifications whenever a market breaches predetermined volatility bands
Academic research: Leverage resolved market records to evaluate forecast performance and calibration

FAQ

Is the Polymarket API free to use?: Absolutely—market data via the Gamma API carries no cost subject to standard rate restrictions (approximately 100 requests per minute without authentication). Submitting orders on the CLOB requires a wallet with sufficient funds, though querying market information remains complimentary.
Is there a Python library for Polymarket?: Community developers have published several Python packages on GitHub. Look for "polymarket-py" to locate actively maintained implementations.