Senior Mainframe Assembler Programmer

Location: Toronto, ON

Onsite Flexibility: Hybrid

• Position Type: Contract
• Contract Duration: 6 months
• Pay Rate: C$65.00–C$80.00 / Hour (CAD)

Our client, a leading Canadian financial institution, is seeking an experienced Senior Mainframe Assembler Programmer to support business-critical banking applications and regulatory technology initiatives. The successful candidate will bring strong hands-on expertise with IBM Assembler / HLASM and deep experience working within enterprise mainframe environments. This role will involve application development, enhancement, testing, production support and technical analysis across complex legacy systems.

• Design, develop, test and implement mainframe application enhancements using Assembler / HLASM.
• Translate business and technical requirements into detailed design specifications and production-quality code.
• Support applications across the full SDLC, from analysis and development through testing, implementation and production support.
• Analyze existing mainframe programs and identify required changes, dependencies and downstream impacts.
• Troubleshoot complex application issues and perform root-cause analysis.
• Work closely with COBOL developers, architects, analysts, QA and infrastructure teams.
• Support regulatory and mandatory-change initiatives impacting core banking applications.
• Ensure solutions meet enterprise standards for security, performance, resiliency, logging and error handling.

• Strong hands-on expertise with IBM Assembler / HLASM.
• Experience with z/OS, CICS, JCL, DB2, VSAM and TSO/ISPF.
• Good working knowledge of COBOL and integrated mainframe application environments.
• Strong debugging, troubleshooting and production-support skills.
• Experience delivering changes through structured SDLC environments.
• Strong communication and collaboration skills.

• Previous experience within banking or financial services strongly preferred.
• Experience supporting Personal Banking or core deposit applications.
• Familiarity with regulatory or compliance-driven technology initiatives.
• Experience with mainframe modernization, APIs or z/OS Connect.

• 5 years of mainframe application development experience.

GTT is a minority-owned staffing firm and a subsidiary of Chenega Corporation, a Native American-owned company in Alaska. We highly value diverse and inclusive workplaces and support Fortune 500 organizations across banking, financial services, technology, life sciences, biotech, utilities, and retail sectors throughout the U.S. and Canada.

Job Number: 26-17412 Industry: Software Engineering