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Polymarket’s CLOB (Central Limit Order Book) is a hybrid-decentralized trading system — offchain order matching with onchain settlement via the Exchange contract (audited by Chainsecurity). All trading is non-custodial. Orders are EIP-712 signed messages, and matched trades settle atomically on Polygon. The operator cannot set prices or execute unauthorized trades. We recommend using the open-source SDK clients, which handle order signing, authentication, and submission:

TypeScript Client

npm install @polymarket/clob-client-v2 viem

Python Client

pip install py-clob-client-v2

Rust Client

cargo add polymarket_client_sdk_v2 —features clob

You can also use the REST API directly, but you’ll need to manage EIP-712 order signing and HMAC authentication headers yourself. See REST API Headers below.

Authentication

The CLOB uses two levels of authentication: You use your private key once to derive L2 credentials (API key, secret, passphrase), which authenticate all subsequent trading requests.

Signature Types

When initializing the trading client, you must specify your wallet’s signature type and funder address:
New API users should use deposit wallets with signature type 3. Existing Proxy and Safe users are unaffected and can keep using signature types 1 and 2. Type 0 is for standalone EOA wallets only.

Initialize the Trading Client


REST API Headers

If you’re using the REST API directly (without the SDK), you need to attach authentication headers to each request. L1 Headers — for creating or deriving API credentials: L2 Headers — for all trading operations (orders, cancellations, queries):
Even with L2 authentication, methods that create orders still require the user’s private key for EIP-712 order payload signing. L2 credentials authenticate the request, but the order itself must be signed by the key.

Client Methods

Public Methods

Market data, orderbooks, prices, and spreads — no auth required.

L1 Methods

Sign orders and derive API credentials with your private key.

L2 Methods

Place orders, cancel orders, query trades, and manage notifications.

Builder Methods

Track orders and trades attributed to your builder code.

Server Infrastructure

The CLOB matching engine runs in the following regions:
  • Primary Servers: eu-west-2
  • Closest Non-Georestricted Region: eu-west-1
Direct co-location available. Users who complete the KYC/KYB form can get access to co-locate directly in eu-west-2 for the lowest possible latency to Polymarket’s primary servers. See Geographic Restrictions for full geographic availability details.

What Is in This Section

Quickstart

Place your first order end-to-end

Orderbook

Reading the orderbook, prices, spreads, and midpoints

Orders

Order types, tick sizes, creating, cancelling, and querying orders

Fees

Fee structure, fee-enabled markets, and maker rebates

Gasless Transactions

Execute onchain operations without paying gas

CTF Tokens

Split, merge, and redeem outcome tokens

Bridge

Deposit and withdraw funds across chains