From legacy complexity to composable banking: How cloud platform engineering and BIAN enable AI-ready banking architectures

Banks face a structural modernization challenge: decades of siloed, monolithic core systems block AI adoption by trapping data in inflexible architectures that cannot support real-time orchestration or scalable automation. The article argues that composable banking—decomposing legacy stacks into loosely coupled, API-driven service components aligned to the Banking Industry Architecture Network (BIAN) standard—provides the architectural foundation required to deploy AI agents and generative AI at enterprise scale. Cloud platform engineering acts as the delivery mechanism, enabling banks to containerize and modularize services while establishing consistent governance, security, and deployment pipelines across hybrid environments. The BIAN semantic model supplies a shared, standardized service domain vocabulary that eliminates integration friction and allows AI systems to reason across previously siloed banking functions. Together, these two approaches create an 'AI-ready' architecture in which new capabilities—fraud detection, personalization, automated decisioning—can be composed and scaled without re-platforming entire cores. The authors position this as a strategic imperative for CIOs and technology leaders in financial services who must balance innovation velocity against regulatory and operational risk.