A list of all Chat APIs, designed to answer the question "What are the best APIs for Chat?" All major Web APIs and mobile API resources related to Chat, including those formatted in XML or JSON and those for use with iOS and the iPhone, are featured on this list. An API (or Application Programming Interface) is a method software applications and programs use to interact with one another, and share data, rules, settings or specifications. APIs interact with applications, libraries, operating systems and more, and are often used for sharing or embedding content. Some of the most popular APIs used around the modern Web are the Google API, the Twitter API, Wikipedia's API and the Ruby API.