Polymarket Bot API Guide: Build Custom Integrations (2026)
Developer guide to building Polymarket bots via the CLOB API. Covers authentication, order management, WebSocket streams, and best practices.
Table of Contents
Authentication and API Keys
Polymarket API authentication uses HMAC-signed requests tied to your wallet private key. Generate API credentials (key, secret, passphrase) via the SDK or Polymarket interface.
The py-clob-client SDK handles signing automatically. For other languages, implement the HMAC-SHA256 signing process per the API documentation. Store credentials securely in environment variables.
Order Management
The API supports creating, cancelling, and querying orders. Create orders with: token_id (YES/NO outcome), side (BUY/SELL), price, size, and order_type (GTC for maker, FOK for taker).
Batch operations improve efficiency: cancel multiple orders in one request, or submit multiple orders atomically. Use order IDs to track status and handle partial fills.
WebSocket Real-Time Data
WebSocket subscriptions provide real-time orderbook updates, trade events, and market changes without polling. Subscribe to specific markets or listen to all market activity.
For latency-sensitive strategies (sniping, arbitrage), WebSockets are essential. REST polling introduces delays of seconds while WebSocket delivers updates in milliseconds.
Best Practices
Use maker (GTC) orders to avoid taker fees. Implement exponential backoff for rate limit handling. Cache market data locally to reduce API calls. Handle WebSocket disconnections gracefully with automatic reconnection.
Log all orders and trades for auditing. Implement kill switches that halt trading on unexpected errors. Monitor your API usage to stay within rate limits.
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Frequently Asked Questions
What are the API rate limits?
Order submission: ~10 per second. Market data REST: higher limits. WebSocket has no rate limit for receiving data. Always check current limits in the API docs.
Can I use the API from JavaScript?
Yes. The CLOB API is REST-based and works from any language. The official SDK is Python but community TypeScript libraries exist.
Is the API free?
Yes. The API itself is free. You pay trading fees only when orders execute.
Where is the API documentation?
Official documentation at docs.polymarket.com covers all endpoints, authentication, and examples.