An API (Application Programming Interface) is a set of functions that permits access to the services of an application, via a programming language. It simplifies access of a developer to a program or an online application by providing a standard set of features and a high level of abstraction by an exchange of parameters. With an API, the developer does not need to know how the application is programmed or know the programming language. APIs have developed very rapidly in the field of geographic information online. [French]