Senior Mainframe Developer (zOS)

Senior Mainframe Developer (zOS Environment) ITTConnect is seeking a Senior Mainframe Developer (zOS Environment) to work on site for a client in the Columbus, OH area. This is a contract position with a client that is a global leader in consulting, digital transformation, technology and engineering services with over 300,000 team members in nearly 50 countries. The end client is in the Utilities sector. Job location: Columbus, OH or Nashville, TN (both locations would be for on site work). We are seeking a Senior Mainframe Developer to support a critical legacy platform (MACSS) as part of a large-scale modernization initiative tied to the adoption of the Gigawatt AI platform. This role sits at the intersection of legacy system stability and modern platform enablement, where core mainframe applications are being API-enabled and integrated into an AI-driven utility platform. You will play a key role in ensuring that foundational systems are scalable, reliable, and ready to support real-time data access and service exposure. Key Responsibilities: Own and support a core mainframe application (MACSS) across production, enhancements, and project initiatives Develop and maintain applications using COBOL, JCL, DB2, and CICS Troubleshoot and resolve production issues across batch and online systems Collaborate with API and platform teams to enable integration via z/OS Connect services Support data flows and service exposure to downstream platforms (APIM, Kafka, etc.) Participate in system design discussions to support modernization and integration efforts Ensure performance, reliability, and scalability of legacy systems Why This Role Matters: This position is critical in enabling the organization's transition to a modern, API-driven architecture by ensuring the stability and scalability of its core legacy systems. Requirements: 8+ years of hands-on mainframe development experience Strong expertise in: COBOL, JCL, DB2, CICS Proven experience supporting production systems and critical applications Experience working in large enterprise environments (preferably utilities, banking, or insurance) Strong debugging and problem-solving skills in complex legacy environments Preferred Qualifications: Utilities industry experience Experience with IBM z/OS Connect Exposure to API enablement of mainframe systems Familiarity with event-driven architectures (Kafka or similar) Experience supporting systems undergoing modernization or digital transformation