Contributed to the development of a digital wallet and loyalty platform serving multiple clients, with two client-specific versions successfully deployed to production. Developed token-based and voucher payment features, integrated an external payment provider, implemented transaction history functionality, and built a secure refund API with operator-specific authorization. Created reusable frontend components, including a QR code scanner supporting multiple payment workflows. This project involved working on business-critical financial processes where security, reliable API integrations, a