How to Get Polymarket Market Data via API
Polymarket is one of the largest prediction markets by volume. Here's how to pull its implied odds programmatically and line them up against sportsbooks, with no wallet and a free tier.
You can get Polymarket market data via API by using an odds aggregation service like SharpAPI. Sign up for a free account, generate an API key, and make a single REST call to get Polymarket implied probabilities normalized alongside 44+ sportsbooks and Kalshi. Polymarket's own APIs exist and are public, but they return markets in USDC keyed by slugs you have to match to games yourself. An aggregator maps that for you so Polymarket lines sit next to sportsbook odds in the same response.
Why Polymarket Market Data Matters
Polymarket is a high-volume prediction market where each market price is a live implied probability. A contract trading at 0.62 USDC means the market prices that outcome at roughly 62 percent. Because Polymarket is an exchange with real money on both sides, its prices are an independent read on an event, separate from how sportsbooks set their lines.
For a developer building betting or analytics tools, that independent read is the value. When Polymarket's implied probability diverges from the sportsbook consensus, the gap is a signal, and sometimes an arbitrage or positive expected value opportunity. To act on it, you need Polymarket prices in the same format and the same call as your sportsbook data, not as raw on-chain USDC keyed by market slugs.
One of the largest prediction markets, deep liquidity on major events
USDC contract price is a direct probability, no vig to remove
Exchange-driven prices, a separate read from sportsbook lines
Your Options for Getting Polymarket Data
| Method | Requirements | Data | Best For |
|---|---|---|---|
| Polymarket CLOB / Gamma API | Public, but USDC pricing and slug-to-event mapping is on you | Polymarket only, own schema | Trading on Polymarket, on-chain apps |
| SharpAPI | Free sign-up, no wallet or on-chain calls | Polymarket + Kalshi + sportsbooks, one schema | Building odds, arbitrage, and EV tools |
| Web scraping | Proxy infrastructure, anti-bot bypass, ongoing maintenance | Polymarket only (fragile) | Not recommended |
Recommendation: If you are building directly on Polymarket, use its CLOB and Gamma APIs. If your goal is to compare Polymarket against sportsbooks and other prediction markets, an aggregation API is the fastest path. You skip the USDC conversions, the slug-to-event mapping, and the per-venue schema work.
Step-by-Step: Get Polymarket Data in 5 Minutes
Create a free SharpAPI account
Sign up at sharpapi.io, no credit card required. You get 12 requests/minute immediately.
Generate an API key
Go to your API Keys dashboard and create a new key. Copy it for use in the Authorization header.
Install the SDK (optional)
npm install @sharp-api/sdk or pip install sharpapi. Or use plain HTTP with any language.
Request Polymarket implied odds
Pass sportsbook=polymarket to filter for Polymarket, or list it with sportsbooks to get everything in one response.
Code Examples
TypeScript (SDK)
const res = await fetch(
'https://api.sharpapi.io/api/v1/odds?sport=basketball&sportsbook=polymarket,pinnacle,draftkings&markets=h2h',
{ headers: { 'X-API-Key': process.env.SHARPAPI_KEY } },
)
const { data } = await res.json()
// One flat array. Each row carries its own sportsbook and implied probability.
for (const row of data) {
console.log(row.selection, row.sportsbook, row.odds_probability)
}Python (SDK)
import requests
res = requests.get(
"https://api.sharpapi.io/api/v1/odds",
params={"sport": "basketball", "sportsbook": "polymarket,pinnacle,draftkings", "markets": "h2h"},
headers={"X-API-Key": "YOUR_API_KEY"},
)
# One flat array. Each row carries its own sportsbook and implied probability.
for row in res.json()["data"]:
print(row["selection"], row["sportsbook"], row["odds_probability"])cURL (any language)
curl -X GET "https://api.sharpapi.io/api/v1/odds?sport=basketball&sportsbook=polymarket,pinnacle,draftkings&markets=h2h" \
-H "X-API-Key: YOUR_API_KEY" \
-H "Accept: application/json"Polymarket vs Sportsbook Consensus
The reason to normalize Polymarket alongside sportsbooks is to spot where they disagree. A Polymarket contract already states an implied probability directly. Convert a sportsbook line to its no-vig fair probability and you can compare the two on the same scale.
Worked Example: Prediction Market vs Sportsbook
Event: Team A to win
Polymarket price: 0.61 -> implied 61.0%
Sportsbook fair odds: -139 -> no-vig 58.0%
Gap = 61.0% - 58.0% = 3.0%
The market and the books disagree by 3 points. Depending on
direction and price, that can be a +EV bet on one side or a
cross-venue arbitrage. SharpAPI flags the gap automatically.SharpAPI's +EV endpoint and arbitrage endpoint compute these gaps across Polymarket, Kalshi, and every covered sportsbook in real time, and can stream them over SSE.