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Overview

Market makers primarily interact with Polymarket through the CLOB (Central Limit Order Book) API to post and manage limit orders.

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Order Entry

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Posting Limit Orders

Use the CLOB client to create and post limit orders: 
import { ClobClient, Side, OrderType } from "@polymarket/clob-client";

const client = new ClobClient(
  "https://clob.polymarket.com",
  137,
  wallet,
  credentials,
  signatureType,
  funder
);

// Post a bid (buy order)
const bidOrder = await client.createAndPostOrder({
  tokenID: "34097058504275310827233323421517291090691602969494795225921954353603704046623",
  side: Side.BUY,
  price: 0.48,
  size: 1000,
  orderType: OrderType.GTC
});

// Post an ask (sell order)
const askOrder = await client.createAndPostOrder({
  tokenID: "34097058504275310827233323421517291090691602969494795225921954353603704046623",
  side: Side.SELL,
  price: 0.52,
  size: 1000,
  orderType: OrderType.GTC
});
See Create Order for full documentation.

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Batch Orders

For efficiency, post multiple orders in a single request: 
const orders = await Promise.all([
  client.createOrder({ tokenID, side: Side.BUY, price: 0.48, size: 500 }),
  client.createOrder({ tokenID, side: Side.BUY, price: 0.47, size: 500 }),
  client.createOrder({ tokenID, side: Side.SELL, price: 0.52, size: 500 }),
  client.createOrder({ tokenID, side: Side.SELL, price: 0.53, size: 500 })
]);

const response = await client.postOrders(
  orders.map(order => ({ order, orderType: OrderType.GTC }))
);
See Post Orders Batch for details.

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Order Types

TypeBehaviorMM Use Case
GTC (Good Till Cancelled)Rests on book until filled or cancelledDefault for passive quoting
GTD (Good Till Date)Auto-expires at specified timeAuto-expire before events
FOK (Fill or Kill)Fill entirely immediately or cancelAggressive rebalancing (all or nothing)
FAK (Fill and Kill)Fill available immediately, cancel restPartial rebalancing acceptable

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When to Use Each

For passive market making (maker orders):
  • GTC - Standard quotes that sit on the book
  • GTD - Time-limited quotes (e.g., expire before market close)
For rebalancing (taker orders):
  • FOK - When you need exact size or nothing
  • FAK - When partial fills are acceptable
// GTD example: expire in 1 hour
const expiringOrder = await client.createOrder({
  tokenID,
  side: Side.BUY,
  price: 0.50,
  size: 1000,
  orderType: OrderType.GTD,
  expiration: Math.floor(Date.now() / 1000) + 3600 // 1 hour from now
});

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Order Management

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Cancel Orders

Cancel individual orders or all orders: 
// Cancel single order
await client.cancelOrder(orderId);

// Cancel multiple orders in a single calls
await client.cancelOrders(orderIds: string[]);

// Cancel all orders for a market
await client.cancelMarketOrders(conditionId);

// Cancel all orders
await client.cancelAll();
See Cancel Orders for full documentation.

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Get Active Orders

Monitor your open orders: 
// Get active order
const order = await client.getOrder(orderId);

// Get active orders optionally filtered
const orders = await client.getOpenOrders({
  id?: string; // Order ID (hash)
  market?: string; // Market condition ID
  asset_id?: string; // Token ID
});
See Get Active Orders for details.

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Best Practices

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Quote Management

  1. Two-sided quoting - Post both bids and asks to earn maximum liquidity rewards
  2. Monitor inventory - Skew quotes based on your position
  3. Cancel stale quotes - Remove orders when market conditions change
  4. Use GTD for events - Auto-expire quotes before known events

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Latency Optimization

  1. Batch orders - Use postOrders() instead of multiple createAndPostOrder() calls
  2. WebSocket for data - Use WebSocket feeds instead of polling REST endpoints

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Risk Management

  1. Size limits - Check token balances before quoting; don’t exceed inventory
  2. Price guards - Validate against book midpoint; reject outlier prices
  3. Kill switch - Use cancelAll() on error or position breach
  4. Monitor fills - Subscribe to WebSocket user channel for real-time fill updates

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Tick Sizes

Markets have different minimum price increments: 
const tickSize = await client.getTickSize(tokenID);
// Returns: "0.1" | "0.01" | "0.001" | "0.0001"
Ensure your prices conform to the market’s tick size.

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Fee Structure

RoleFee
Maker0 bps
Taker0 bps
Current fees are 0% for both makers and takers. See CLOB Introduction for fee calculation details.

CLOB Client Overview

Complete client method reference

L2 Methods

Authenticated order management methods

WebSocket Feeds

Real-time order and market data

Liquidity Rewards

Earn rewards for providing liquidity