Polymarket provides APIs for accessing prediction market data programmatically. Here's how to get started with Polymarket's data.
API Overview
Polymarket offers several ways to access data:
- REST API: Fetch market data, prices, and order books
- WebSocket: Real-time price updates
- GraphQL: Query historical data
- Subgraph: On-chain data via The Graph
Common Data Points
- Market list: All active prediction markets
- Current prices: Yes/No prices for each outcome
- Order books: Bid/ask depth
- Historical prices: Price charts over time
- Volume: Trading activity per market
Common Use Cases
- Price tracking: Monitor odds across markets
- Arbitrage detection: Compare Polymarket to other platforms
- Data analysis: Historical accuracy research
- Trading bots: Automated market making
- Visualizations: Build custom election maps
Getting Started
Check Polymarket's documentation and GitHub for the latest API specifications. The API is generally permissive for read operations.
How to get a Polymarket API key
API-key intent usually means one of two things: you want public market data, or you want authenticated trading access. Public market data can often be read without the same permissions needed for order placement. Trading requires wallet-connected credentials and request signing. Keep API secrets, passphrases, and private keys out of source control.
If your search is "how to get Polymarket API key," start by deciding whether you need read-only market data, CLOB order-book access, or authenticated trading. Most research workflows only need prices, market metadata, volume, and historical movement. Trading-bot workflows need stricter key handling, position limits, and failure controls.
CLOB API, order books, and trading bots
The CLOB API is the important layer for developers who care about execution. It exposes order-book depth, bids, asks, token IDs, and market structure. A bot that only reads the last traded price is incomplete because it does not know whether the price is actually fillable.
Before building a Polymarket trading bot, verify:
- Liquidity: enough depth exists at the price your strategy expects.
- Spread: the bid-ask gap does not erase the edge.
- Resolution rules: the bot knows what the contract actually asks.
- Rate limits: polling and order placement stay inside allowed usage.
- Kill switch: the bot can cancel orders and stop trading after errors.
For a full execution walkthrough, read the Polymarket trading bot tutorial. If you want the same developer lens on Kalshi, compare it with the Kalshi API guide and Kalshi trading bot GitHub guide.
Use Alphascope for Aggregated Data
Don't want to build your own integration? Alphascope aggregates data from Polymarket and Kalshi:
- Predictions → View all markets in one place
- News → See news linked to market movements
- Wallet tracker → Use wallet movement as a research signal before automating anything
- Polymarket vs Kalshi → Compare platform access, APIs, fees, and liquidity