The Gemini Private API Curl Sample Code demonstrates how to create payloads. All requests must contain a nonce, a number that will never be repeated and must increase between requests. This is to prevent an attacker who has captured a previous request from simply replaying that request.
ErisX, cryptocurrency derivatives platform provider, has announced a new REST API for its Block trading facility. Through the API, users can trade spot and regulated-futures products for all exchanges available through ErisX. Currently, that includes Bitcoin, Bitcoin cash, Ether, and Litecoin.