Plesk provides full support for the PHP scripting language, including support for multiple PHP versions and handler types out of the box. This topic lists the PHP handler types that can be used in Plesk.

Handler type Performance Memory usage Handler details
Apache module High Low This handler is only available in Plesk for Linux. It is the least secure option as all PHP scripts are executed on behalf of the apache user. This means that all files created by PHP scripts of any plan subscriber have the same owner (apache) and the same permission set. Thus, it is possible for a user to affect the files of another user or some important system files. You can avoid some security issues by turning the PHP safe_mode option on. This disables a number of PHP functions that have potential security risks. This may lead to inoperability of some web apps. The safe_mode option is considered to be obsolete and was removed in PHP 5.4.
ISAPI extension High Low This handler is only available in Plesk for Windows. The ISAPI extension can provide site isolation if a dedicated IIS application pool is switched on for subscriptions. Site isolation means that the sites of different customers run their scripts independently. Thus, an error in one PHP script does not affect the work of other scripts. In addition, PHP scripts run on behalf of a system user associated with a hosting account. The ISAPI extension handler is not supported starting from PHP 5.3
CGI application Low Low The CGI handler provides PHP script execution on behalf of a system user associated with a hosting account. On Linux, this behavior is possible only when the suEXEC module of the Apache web server is on (default option). In other cases, all PHP scripts are executed on behalf of the apache user. By default, the CGI handler is unavailable to Plesk customers.
FastCGI application High High The FastCGI handler runs PHP scripts on behalf of a system user associated with a hosting account.
PHP-FPM application High Low This handler is only available in Plesk for Linux. The PHP-FPM is an advanced version of FastCGI which offers significant benefits for highly loaded web applications.