Skip to main content
Graylayer provides two APIs for accessing prediction market and crypto data:
  • Market Proxy (gateway.graylayer.tech) — a unified REST and WebSocket gateway for Polymarket, Kalshi, Gemini, Coinbase, and Forecastex. One API key, all platforms.
  • Orderbook History API (data.graylayer.tech) — historical orderbook snapshots and deltas from Kalshi, Gemini, and Polymarket US.

​
Getting a key

API keys are issued via Discord. Join the server, go to the Community tab, and post a request in #api-key-request.

Join the Graylayer Discord

Request an API key in #api-key-request under the Community tab.

​
Market Proxy

All requests go to http://gateway.graylayer.tech/api/v1/{platform}/{resource}. The proxy validates your X-API-Key, forwards the request to the upstream platform, injects any required credentials (e.g. Kalshi RSA-PSS signatures), and returns the upstream response unchanged.

Polymarket

Markets, events, order books, prices, profiles, and trades.

Kalshi

Markets, events, order books, portfolio, and historical data.

Gemini

Prediction market categories, events, and market data.

Forecastex

IBKR event contract data with open interest (read-only).

Coinbase

Spot exchange market data. US-friendly. Public endpoints, no auth needed.

​
Orderbook History API

http://data.graylayer.tech — query historical snapshots and deltas for any ticker across exchanges.

Overview & auth

Authentication, rate limits, anonymous access, and admin API.

Endpoints

Tickers, snapshots, deltas — with full query parameter reference and examples.