Polymarket API guide

Polymarket publishes its market data through free public APIs, and lets you trade programmatically through its order book (the CLOB). Reading prices, markets and leaderboards needs no account at all; placing orders needs a funded Polymarket wallet and API credentials. This guide maps out the APIs, shows working requests, and explains authentication, based on Polymarket’s documentation as of October 2026.

The APIs at a glance

Reading markets with the Gamma API

The quickest way to see what’s trading. This returns the five open events with the most volume in the last 24 hours:

curl "https://gamma-api.polymarket.com/events?active=true&closed=false&order=volume24hr&ascending=false&limit=5"

Each event contains its markets. For every market, outcomePrices is a JSON-encoded string such as ["0.62", "0.38"]: the first value is the Yes price, which is also the implied probability. Multi-candidate events, like an election with many candidates, contain one yes/no market per candidate, named in groupItemTitle. Useful fields include volume24hr, oneDayPriceChange, endDate and closed.

To fetch one event by its numeric id:

curl "https://gamma-api.polymarket.com/events/12345"

Leaderboards and activity with the Data API

curl "https://data-api.polymarket.com/v1/leaderboard?timePeriod=MONTH&orderBy=PNL&limit=25"

timePeriod takes DAY, WEEK, MONTH or ALL; orderBy takes PNL or VOL; an optional category narrows it to POLITICS, SPORTS or CRYPTO. See it running in our live Polymarket leaderboard. The older lb-api.polymarket.com service has been retired.

Order books and live prices

The CLOB serves prices and order books without authentication, and the market WebSocket pushes updates as they happen, which is better than polling if you need real-time data. Subscribe with the token IDs of the outcomes you care about (found in each market’s clobTokenIds on Gamma).

Trading: how authentication works

Placing orders uses two levels of authentication:

1. L1, proving you own the wallet. Your signer key signs an EIP-712 message (ClobAuth, on Polygon, chain ID 137) that attests you control the address.
2. L2, API credentials. Send that signature to POST /auth/api-key to create an API key, secret and passphrase, or GET /auth/derive-api-key to recover existing ones. Every private request is then signed with HMAC-SHA256 using the secret, and sent with POLY_API_KEY, POLY_PASSPHRASE, POLY_SIGNATURE, POLY_TIMESTAMP and POLY_ADDRESS headers.

Orders themselves are also signed by the wallet. Polymarket supports several wallet types: Deposit Wallets (the default for accounts created since May 4, 2026), older proxy wallets created by email or Google sign-in, Safe wallets created with MetaMask-style signers, and allowlisted plain wallets (EOAs), which pay their own gas in POL.

Rules and limits

• Geographic restrictions apply to the API too. Countries that are close-only or blocked on Polymarket, including the US for the main exchange, are restricted on the trading API as well. See Is Polymarket legal? Polymarket US has its own separate documentation.
• Rate limits depend on your tier. Heavier users can join Polymarket’s Builder Program for higher limits.
• Fees apply to taker orders in most categories; makers pay nothing. See the fee table in our Polymarket profile.

FAQ

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