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 work, investigative journalism, and analytical projects. Through PolyGram, the Polymarket platform—the globe's foremost prediction market—provides comprehensive APIs that enable builders to leverage an extensive dataset of market intelligence.

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 prediction markets for particular occurrences
News tools: Identify markets responding to emerging events and news cycles
Aggregators: Benchmark odds and implied probabilities across Polymarket, Kalshi, and Metaculus
Alert systems: Trigger notifications whenever a market experiences significant price movement
Academic research: Utilise historical resolution records to evaluate prediction accuracy and model performance

FAQ

Is the Polymarket API free to use?: Yes — market data via the Gamma API carries no cost, subject to rate restrictions (approximately 100 requests per minute without authentication). Submitting orders on the CLOB requires an active wallet, though retrieving data remains complimentary.
Is there a Python library for Polymarket?: Multiple community-developed Python libraries are available on GitHub. Look for "polymarket-py" to discover the most actively maintained versions.