Server application programming interface

In computer science, the Server Application Programming Interface (SAPI) is the generic term used to designate direct module interfaces to web server applications such as the Apache HTTP Server, Microsoft IIS, or iPlanet. Microsoft also uses the term in ISAPI and the defunct Netscape used the term NSAPI. As an example, PHP has a direct module interface called a SAPI for different web servers. For PHP 5 and Apache 2.0 on Windows, it is in the form of a DLL file called php5apache2.dll. The DLL is a module that provides an interface between PHP and the web server, written in a form that the server understands. This form is what is known as a SAPI.

There are different kinds of SAPIs for different languages. For example, the most common SAPIs for PHP language are PHP CLI and CGI.