Source code file written for FastCGI (FCGI), an extension of CGI standard used for more robust handling of Web server requests; may be written in one of many supporting languages but often written in Perl, and therefore contains both Perl code and code from the FastCGI API.

The FastCGI interface includes support for distributed computing so that Web requests can be load balanced across multiple servers. It also includes support for authentication and access roles. NOTE: FastCGI is supported by many Web servers natively or through Web server extensions.