F. Keller developed a new PayPal Customer Vault Token Retrieval API route for the shopware/SwagPayPal repository, centralizing the logic for fetching customer vault tokens to enhance both security and maintainability in payment data management. Working primarily with PHP, Keller applied backend development and API design skills to implement exception handling and update dependent services to use the new route. This work established a more secure and scalable foundation for future PayPal integration features. Although the scope was focused, the solution addressed a core architectural need, reducing maintenance effort and improving the overall robustness of the payment gateway integration.