The server requirements for WHMCS are as follows:
Web server: Any that supports PHP (for example, Apache or Nginx).
PHP Version: 7.2 or later (PHP 7.4 preferred).
Database: MySQL 5.6 or later (MariaDB is also supported).
Web Server Extensions: PHP extensions such as PDO, cURL, SimpleXML, GD, and JSON are examples of web server extensions.
SSL Certificate: This is highly recommended for secure transactions.