Using the Polymarket Data API: Real-Time Prediction Market Data for Developers | Who Will Win

In this guide

Available Data Endpoints
Python Quickstart
Use Cases
FAQ

Developers seeking to leverage forecasting intelligence now have access to comprehensive market datasets through the Polymarket ecosystem, available via PolyGram's infrastructure. The platform's robust APIs unlock deep analytical capabilities for those building research tools, editorial applications, and algorithmic trading systems atop the globe's premier prediction market 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 probability shifts across specific outcomes and timeframes
News tools: Identify markets responding to emerging developments
Aggregators: Benchmark implied odds between Polymarket, Kalshi, and Metaculus platforms
Alert systems: Trigger notifications upon significant market movement thresholds
Academic research: Analyse settled outcomes for forecast quality assessment and model validation

FAQ

Is the Polymarket API free to use?: Absolutely — the Gamma API provides complimentary access to market intelligence (subject to ~100 requests per minute without authentication). CLOB order placement demands a wallet with funds, though data retrieval remains at no cost.
Is there a Python library for Polymarket?: Multiple community-driven Python packages are available on GitHub. Look for "polymarket-py" to locate the most actively maintained implementations.