Developer Resources

For developers, WHMCS has all the capabilities you might need to allow you to customize, integrate & extend the core system into your own website & applications.

Display Customisation

These articles provide help & information with customising your WHMCS system.

• Template Syntax
• Client Area Templates
• Admin Area Templates
• Order Form Templates
• PDF Invoice
• Client Area Language Files
• Admin Area Language Files

Extending Functionality

These documents provide information on how to extend and integrate WHMCS with additional third party systems.

• Module Development Kit - guide & template for creating your own product/server provisioning modules
• Registrar Development Kit - guide & template for creating a domain registrar module
• Gateway Development Kit - guide & template for creating a payment gateway module
• Addon Modules - addon modules allow you to create both custom admin pages and hooks for additional functionality
• Creating Pages - demonstrates how to create custom pages for the client area
• Action Hooks - hooks allow you to run your own code when various events & actions occur inside WHMCS
• AutoAuth - for automatically authenticating clients from custom code

API

These API articles provide details about interfacing with the WHMCS API from your own custom code & applications:

• API Information - overview & setup info
• Internal API - details & example code for calling the WHMCS API locally from within WHMCS modules & files
• Example XML Method Code - sample PHP code for calling & interpreting the XML responses of the WHMCS API
• Example JSON Method Code - sample PHP code for calling & interpreting JSON responses from the WHMCS API
• API Functions - individual documentation for all the functions of the API