Abstract: In an era of accelerated digital payments, securing financial transactions goes far beyond encryption and authentication. This study presents an enhanced, multidimensional framework for smart payment system security that integrates developer-led secure software design, explainable AI, cross-border compliance, and inclusive user experience. By examining evolving threats—including biometric spoofing, blockchain exploits, and quantum computing—this research proposes advanced threat modeling strategies for next-generation payment architectures. It also addresses systemic challenges such as integrating DevSecOps in CI/CD pipelines, achieving legal interoperability across jurisdictions, and mitigating bias in AI-driven fraud detection. Drawing on case studies from FinTech, remittance, and e-commerce ecosystems, the framework emphasizes usability, governance, and transparency as pillars of long-term trust. The study concludes with strategic recommendations for developers and financial institutions aiming to build secure, scalable, and ethically sound digital payment platforms equipped to meet the demands of a global, interconnected economy.

Keywords: Smart Payment Security, DevSecOps, Blockchain and Identity Verification, Fraud Detection, CI/CD Pipeline Integration

| DOI: 10.17148/IARJSET.2023.107135