Version 6.x System Requirements

From WHMCS Documentation

Most current web servers* with PHP & MySQL installed will be capable of running WHMCS.

The following table shows the minimum and recommended system requirements for running WHMCS 6.0 and later.

Requirement Minimum Recommended
PHP Version 5.3.7 Latest 5.6.x Release
PHP Memory Limit 64MB 128MB**
PHP Database Extension PDO PDO
PHP Extensions Curl with SSL

GD2 Image Library
JSON Support

Curl with SSL

GD2 Image Library
JSON Support

MySQL Version 5.1.0 5.5.x
MySQL Strict Mode Disabled Disabled
Ioncube Loaders 4.6.1 4.7.5

WHMCS Version 6.0 supports PHP 5.3.7 or later, including PHP 5.4, 5.5 and 5.6.

While these are the minimum requirements, we strongly recommend using the latest available, stable releases of all software and extensions. Recommended suggestions are correct as at 2nd February 2016.

Looking for the requirements for the WHMCS 5.x series? Click here

* We validate WHMCS to run in Linux based environments running the Apache web server. Other environments such as Windows based configurations may experience compatibility issues and are not supported.

** Memory requirements vary depending upon the size and volume of activity in an installation. Your exact requirements may differ.