Update: Acquia shutdown Cloud API v1 on 1 July 2020.
The Acquia Cloud API makes it easy to manage sites on the platform. The API allows you to perform many administrative tasks including creating, destroying and copying databases, deploying code, managing domains and copying files.
Acquia offers 2 official clients. The primary client is a drush plugin which can only be downloaded from Acquia Insight. The other is a PHP library which states in the README that it is “[n]ot ready for production usage”.