Modernizing legacy financial systems with Api-Driven Architectures

Koritala, Surendra N (2025) Modernizing legacy financial systems with Api-Driven Architectures. World Journal of Advanced Engineering Technology and Sciences, 14 (3). pp. 450-461. ISSN 2582-8266

Today’s financial industry is progressing to adopt novel solutions that would help address the problem of outdated IT infrastructures together with the demands of a complex digital environment. This research paper provides a review of how such modernization can be attained, with particular emphasis in the value of architectures that employ APIs in harmonizing the link between traditional tense financial systems and contemporary applications. From secondary research, the context examines the main API structures: RESTful, GraphQL, and SOAP to emphasise mainly about these architectures: Scalability, Interoperability, and Performance. Through a detailed examination of architectural workflows as well as code samples, this paper shows that APIs enable basic capabilities such as routing, data sharing, and authentication while grappling with the challenges posed by legacy systems. RESTful APIs are introduced here as the simplest and quickest approach; GraphQL for its fine-grain data transfer; and, SOAP as providing the highest level of security for data transmission while dealing with sensitive financial transactions. Taken together, these architectures collectively help the financial institutions to gain in operational flexibility, advance user experiences and undergird innovation. These results point out that the API-driven modernization is not simply the technological transformation but the evolutionary necessity for maintaining the competitiveness of the financial sector at the international level. APIs enable organizations to support compliance needs, embrace new technologies, improve the client experience, and maintain core systems of record’s integrity. Through the analysis of technical concepts and comparative effects on financial organizations, this paper establishes their API’s importance in building the future. When applying the developed API-First approach, the research finds that modernisation is crucial for closing the remaining gap between core systems and digitalisation to support the sustainable and adaptable business growth of financial institutions.