Most current web servers with PHP & MySQL installed will be capable of running WHMCS. However, the specific system requirements are:
  • Windows or Linux OS
  • PHP Version 5.0.x - 5.4.x (with JSON)
  • MySQL Version 4.1.x and above (Strict Mode Disabled)
  • Curl Support (with SSL)
  • GD2 Image Library
  • Ioncube Loaders 4.x or later

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Required file & folders permissions (unless your php is suPHP or PHPSuExec):

/configuration.php CHMOD 644 Writeable
/attachments CHMOD 777 Writeable
/downloads CHMOD 777 Writeable
/templates_c CHMOD 777 Writeable