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Step 1: Get your API keys

  1. Download the app - Get the Polymarket US app and create an account.
  2. Complete identity verification - You’ll be asked to verify your identity before you can trade or access the API. Once approved, you’ll see a confirmation in the app.
Approved to Start Trading
  1. Go to the developer portal - Visit polymarket.us/developer and sign in with the same method you used in the app (Apple, Google, or email).
Developer Portal
  1. Create an API key - Click to create a new key. You’ll get a Key ID and a Secret Key.
Create API Key
Your secret key is shown only once. Copy it somewhere safe before closing the dialog.
If you need help getting set up or need an invite code to access the app, email sami@polymarket.com.

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Step 2: Install the SDK

npm install polymarket-us
TypeScript requires Node.js 18+. Python requires 3.10+.

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Step 3: Configure the client

import { PolymarketUS } from 'polymarket-us';

const client = new PolymarketUS({
  keyId: process.env.POLYMARKET_KEY_ID,
  secretKey: process.env.POLYMARKET_SECRET_KEY,
});

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Step 4: Fetch market data

No authentication required for public endpoints. 
const client = new PolymarketUS();

const events = await client.events.list({ limit: 10, active: true });
const market = await client.markets.retrieveBySlug('chiefs-super-bowl');
const book = await client.markets.book('chiefs-super-bowl');

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Step 5: Place an order

const order = await client.orders.create({
  marketSlug: 'chiefs-super-bowl',
  intent: 'ORDER_INTENT_BUY_LONG',
  type: 'ORDER_TYPE_LIMIT',
  price: { value: '0.55', currency: 'USD' },
  quantity: 100,
  tif: 'TIME_IN_FORCE_GOOD_TILL_CANCEL',
});

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Check your account

const balances = await client.account.balances();
const positions = await client.portfolio.positions();
const openOrders = await client.orders.list();

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Error handling

import {
  AuthenticationError,
  BadRequestError,
  NotFoundError,
  RateLimitError,
} from 'polymarket-us';

try {
  const order = await client.orders.create({ marketSlug: '...' });
} catch (error) {
  if (error instanceof AuthenticationError) {
    console.error('Invalid credentials');
  } else if (error instanceof BadRequestError) {
    console.error('Invalid parameters:', error.message);
  } else if (error instanceof RateLimitError) {
    console.error('Rate limited');
  } else if (error instanceof NotFoundError) {
    console.error('Not found');
  }
}
ErrorDescription
AuthenticationErrorInvalid or missing credentials
BadRequestErrorInvalid request parameters
NotFoundErrorResource not found
RateLimitErrorRate limit exceeded
APITimeoutErrorRequest timed out
APIConnectionErrorNetwork connection error

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Next steps

TypeScript SDK

Full SDK reference for TypeScript.

Python SDK

Full SDK reference for Python.

API Reference

Explore all REST endpoints.

WebSockets

Stream live market data.