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This guide covers how to create and post orders on the Polymarket CLOB, including limit orders, market orders, and batch orders.

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Order Types

The CLOB supports four order types:
  • GTC (Good-Til-Canceled): Order stays active until filled or manually canceled
  • GTD (Good-Til-Date): Order expires at a specified timestamp
  • FOK (Fill-Or-Kill): Order must fill completely immediately or be canceled
  • FAK (Fill-And-Kill): Order fills as much as possible immediately, unfilled portion is canceled

​
Creating a Basic Limit Order

Limit orders let you specify an exact price at which you want to buy or sell. 
import { ClobClient, Side, OrderType } from "@polymarket/clob-client";
import { ethers } from "ethers";

const wallet = new ethers.Wallet("your-private-key");
const host = "https://clob.polymarket.com";
const chainId = 137; // Polygon mainnet

// Initialize client with API credentials
const clobClient = new ClobClient(
  host,
  chainId,
  wallet,
  {
    key: "your-api-key",
    secret: "your-secret",
    passphrase: "your-passphrase"
  }
);

// Create a BUY order
const order = await clobClient.createOrder({
  tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
  price: 0.52,      // Price per share (0.52 = 52 cents)
  size: 100,        // Number of shares
  side: Side.BUY,   // Side.BUY or Side.SELL
});

// Post the order to the exchange
const response = await clobClient.postOrder(order, OrderType.GTC);
console.log("Order posted:", response);

​
Order Parameters

​
tokenID
string
required
The token ID of the outcome you want to trade. Get this from the Markets API.
​
price
number
required
Price per share between 0.0001 and 0.9999. Must align with the market’s tick size.
​
size
number
required
Number of shares to buy or sell.
​
side
Side
required
Either Side.BUY or Side.SELL.
​
feeRateBps
number
Fee rate in basis points. If not provided, the market’s fee rate is used automatically.
​
nonce
number
Nonce for on-chain cancellations. Auto-generated if not provided.
​
expiration
number
Unix timestamp when the order expires. Required for GTD orders.
​
taker
string
Address of specific taker. Use zero address for public orders (default).

​
Create and Post in One Step

Use createAndPostOrder() to combine order creation and posting: 
const response = await clobClient.createAndPostOrder(
  {
    tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
    price: 0.52,
    side: Side.BUY,
    size: 100,
  },
  { tickSize: "0.01", negRisk: false },  // Options
  OrderType.GTC,  // Order type
  false,          // deferExec
  false           // postOnly
);

​
Post-Only Orders

Post-only orders ensure your order adds liquidity to the book rather than taking existing liquidity. They’re rejected if they would match immediately. 
const order = await clobClient.createOrder({
  tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
  price: 0.50,
  side: Side.BUY,
  size: 100,
});

// Post-only is only supported for GTC/GTD orders
const response = await clobClient.postOrder(
  order,
  OrderType.GTC,
  false,  // deferExec
  true    // postOnly - order will be rejected if it would match immediately
);

​
Market Orders

Market orders execute immediately at the best available price.

​
Market Buy Order

// Create a market buy order for $100 worth of shares
const marketBuyOrder = await clobClient.createMarketOrder({
  tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
  amount: 100,           // Dollar amount to spend
  side: Side.BUY,
  orderType: OrderType.FOK,  // FOK or FAK
});

// Post the order
const response = await clobClient.postOrder(marketBuyOrder, OrderType.FOK);

​
Market Sell Order

// Create a market sell order for 100 shares
const marketSellOrder = await clobClient.createMarketOrder({
  tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
  amount: 100,           // Number of shares to sell
  side: Side.SELL,
  orderType: OrderType.FOK,
});

const response = await clobClient.postOrder(marketSellOrder, OrderType.FOK);

​
Create and Post Market Order

const response = await clobClient.createAndPostMarketOrder(
  {
    tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
    amount: 100,
    side: Side.BUY,
    orderType: OrderType.FOK,
  },
  { tickSize: "0.01" },
  OrderType.FOK
);
For BUY orders, amount is the dollar amount to spend. For SELL orders, amount is the number of shares to sell.

​
Batch Orders

Post multiple orders in a single request for better performance: 
import { PostOrdersArgs } from "@polymarket/clob-client";

// Create multiple orders
const orders: PostOrdersArgs[] = [
  {
    order: await clobClient.createOrder({
      tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
      price: 0.40,
      side: Side.BUY,
      size: 100,
    }),
    orderType: OrderType.GTC,
    postOnly: false,
  },
  {
    order: await clobClient.createOrder({
      tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
      price: 0.45,
      side: Side.BUY,
      size: 100,
    }),
    orderType: OrderType.GTC,
    postOnly: false,
  },
  {
    order: await clobClient.createOrder({
      tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
      price: 0.55,
      side: Side.SELL,
      size: 100,
    }),
    orderType: OrderType.GTC,
    postOnly: true,
  },
];

// Post all orders in one request
const response = await clobClient.postOrders(
  orders,
  false,  // deferExec
  false   // defaultPostOnly
);

​
GTD Orders with Expiration

Good-Til-Date orders expire at a specific timestamp: 
const oneDayFromNow = Math.floor(Date.now() / 1000) + 86400;

const order = await clobClient.createOrder({
  tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
  price: 0.52,
  side: Side.BUY,
  size: 100,
  expiration: oneDayFromNow,  // Unix timestamp
});

const response = await clobClient.postOrder(order, OrderType.GTD);

​
Order Options

​
Tick Size

Each market has a minimum tick size that determines price precision. The client fetches this automatically, but you can override it: 
const order = await clobClient.createOrder(
  {
    tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
    price: 0.520,  // Price must be multiple of tick size
    side: Side.BUY,
    size: 100,
  },
  { tickSize: "0.01" }  // Valid values: "0.1", "0.01", "0.001", "0.0001"
);

​
Negative Risk

Some markets use negative risk tokens. Specify this in order options: 
const order = await clobClient.createOrder(
  {
    tokenID: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
    price: 0.52,
    side: Side.BUY,
    size: 100,
  },
  { negRisk: true }
);

​
Getting Order Details

Retrieve order information after posting: 
// Get a specific order by ID
const order = await clobClient.getOrder("0x123...");

// Get all open orders
const openOrders = await clobClient.getOpenOrders();

// Filter by market or token
const marketOrders = await clobClient.getOpenOrders({
  market: "0x5f65177b394277fd294cd75650044e32ba009a95022d88a0c1d565897d72f8f1",
});

const tokenOrders = await clobClient.getOpenOrders({
  asset_id: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
});

​
Canceling Orders

1

Cancel a Single Order

await clobClient.cancelOrder({ orderID: "0x123..." });
2

Cancel Multiple Orders

const orderHashes = ["0x123...", "0x456...", "0x789..."];
await clobClient.cancelOrders(orderHashes);
3

Cancel All Orders

await clobClient.cancelAll();
4

Cancel Orders by Market

await clobClient.cancelMarketOrders({
  market: "0x5f65177b394277fd294cd75650044e32ba009a95022d88a0c1d565897d72f8f1",
});

// Or by token ID
await clobClient.cancelMarketOrders({
  asset_id: "71321045679252212594626385532706912750332728571942532289631379312455583992563",
});

​
Troubleshooting

Ensure your price is a multiple of the market’s tick size. The error message shows the minimum and maximum valid prices:
Error: invalid price (0.523), min: 0.01 - max: 0.99
For a tick size of 0.01, valid prices are 0.01, 0.02, 0.03, etc.
If using postOnly: true, your order was rejected because it would have matched immediately. Either:
  • Adjust your price to not cross the spread
  • Use postOnly: false to allow immediate matching
Check your balance and allowance:
const balance = await clobClient.getBalanceAllowance({
  asset_type: AssetType.COLLATERAL,
});
console.log("Balance:", balance.balance);
console.log("Allowance:", balance.allowance);
Ensure you’ve initialized the client with valid API credentials. See Managing API Keys for details.
The tick size you specified is smaller than the market’s minimum:
Error: invalid tick size (0.001), minimum for the market is 0.01
Either omit the tick size to use the market’s default, or specify a larger value.

​
Next Steps

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