New to WHMCS development?
WHMCS is the leading client management, billing, and support platform for web hosting businesses. These docs show you how to extend and integrate it — build a custom client area, automate provisioning, accept payments, hook into events, and call the API. Pick a topic below to dive in.
Explore the documentation
Themes
Customize the client area and order forms to match your brand.
Provisioning Modules
Automate creating, suspending, and terminating services.
Addon Modules
Extend WHMCS with your own admin and client-area functionality.
Payment Gateways
Accept payments through any provider — hosted or merchant.
Domain Registrars
Integrate domain registration, transfers, and syncing.
Hooks
Run your own code at key points throughout WHMCS.
Internal API
Call WHMCS actions from your own applications and scripts.
REST API (v2)
The modern RESTful interface to WHMCS.
Class Reference
Reference for WHMCS's developer-facing model classes.
Advanced
Authentication, database access, logging, widgets, and more.