Secure API Product Design for Open Banking and PSD2 Compliant Platforms

Abstract

Open banking has fundamentally transformed the financial services landscape by enabling secure data sharing and service interoperability through standardized application programming interfaces (apis). Under regulatory frameworks such as the second payment services directive (psd2), financial institutions are required to expose customer-authorized data and payment initiation capabilities to licensed third-party providers. While this paradigm fosters innovation and competition, it also introduces significant security, privacy, and operational risks. Apis have become primary attack surfaces for fraud, data leakage, and service disruption in open financial ecosystems. This paper examines secure api product design principles tAIlored for open banking and psd2-compliant platforms. It presents a comprehensive analysis of regulatory requirements, threat models, authentication and authorization mechanisms, consent management, api governance, and operational resilience strategies. By synthesizing industry best practices, academic research, and regulatory guidance, the study proposes a secure-by-design api product framework that integrates strong customer authentication, fine-grAIned access control, cryptographic assurance, and continuous risk monitoring. The paper further discusses implementation challenges, architectural trade offs, and future directions for secure api ecosystems. The findings emphasize that security in open banking apis must be treated as a core product capability rather than a technical afterthought, ensuring trust, compliance, and sustAInable innovation.