If you do not know the cause of a problem, troubleshooting helps you learn more about it. We recommend trying basic steps to gather information before you contact WHMCS support.
WHMCS includes a large number of apps and integrations that we ship with WHMCS by default, and you can find more apps and integrations from the WHMCS Marketplace.
Use hooks to create custom widgets that display to admins in the Admin Area Dashboard on self-hosted WHMCS installations. You can also customize WHMCS's included widgets.
Modules in WHMCS use templates to define what users see. You can customize these module templates using WHMCS's overrides system on self-hosted WHMCS installations.
Duplicate the open-source Bank Transfer and Mail In Payment payment gateway modules and use them for creating your own custom modules on self-hosted WHMCS installations.