Replace Legacy Smarty Tags

We plan to permanently remove support for legacy Smarty tags in WHMCS 9.0. You must remove these tags from your customizations.


File sessions and database sessions can help you preserve data across subsequent page loads within your custom web applications.

Themes and Templates

Custom hemes and templates alter the Client Area's appearance to match your branding and tailor your offerings to your business's needs.


Transliteration converts text from one writing system into another. You can use transliteration to replace characters in client profile data.

WHMCS Base URL Template Variable

System theme template files require a correct system URL for AJAX calls to function correctly and to find and access required resources.

Single Sign-On into WHMCS

Single Sign-on allows trusted applications and third parties to log users in to WHMCS automatically, without reauthentication.