In the rapidly evolving financial services sector, a robust data modeling strategy is essential to manage the increasing volume of data driven by digital banking expansion. Financial institutions use data to power applications, analyze risks, and make informed decisions, with data modeling significantly impacting performance, scalability, and development speed. As fintechs pose a growing competitive threat, 24% of retail banks have prioritized data platforms and management in their IT spending for 2024-2025. The document-oriented MongoDB database is becoming a popular choice among leading financial institutions, including seven of the top ten banks globally, due to its flexibility, scalability, and ability to handle diverse data types. MongoDB supports modernization efforts by enabling banks to integrate open finance ecosystems, provide personalized banking experiences, and enhance data security and compliance, while its dynamic schema allows for rapid application development and adaptation to changing business needs. This iterative approach to modernization helps banks preserve legacy components while embarking on digital transformation journeys.