Custody API & Mainframe Modernization Specialist

Overview The company is supporting a strategic modernization initiative for one of the world's leading global custodians. The program's objective is to stabilize and modernize a legacy custody accounting platform while preparing for its eventual migration to Finbourne. We are seeking a Custody API & Mainframe Modernization Specialist who combines deep experience with legacy IBM mainframe technologies and modern API architecture. This individual will play a critical role in exposing legacy custody functionality through secure, scalable services while preserving business functionality throughout the modernization journey. This consultant will become part of the initial anchor team responsible for establishing the foundation of a multi-year transformation program. Responsibilities Design API strategies that expose legacy custody accounting functionality. Develop integration approaches between IBM mainframe applications and modern cloud architectures. Analyze existing COBOL, CICS, DB2, VSAM, and batch processing workflows to identify modernization opportunities. Partner with architecture, infrastructure, and business teams to define service-based integration patterns. Support incremental modernization while minimizing operational risk. Design secure RESTful APIs and event-driven services. Participate in application decomposition and modernization planning. Produce technical documentation and integration standards. Support production implementations and issue resolution. Mentor development teams on legacy modernization best practices.