Are there any specific security concerns to be aware of when using a PayPal class in PHP?

One specific security concern when using a PayPal class in PHP is the potential for sensitive data, such as API credentials, to be exposed if not properly secured. To mitigate this risk, it is important to store these credentials securely, such as in a separate configuration file outside of the web root, and restrict access to this file.

// Store API credentials in a separate configuration file
$config = include('config.php');

// Use the credentials in your PayPal class
$paypal = new PayPal($config['api_username'], $config['api_password']);