Mainframes Developer Jobs in Quebec (NOW HIRING)

 Specialist Software Development - Critical Systems SME 

 
At CN, everyday brings new and exciting challenges. You can expect an interesting environment where you're part of making sure our business is running optimally and safely-helping keep the economy on track. We provide the kind of paid training and opportunities that long-term careers are built on and we recognize hard workers who strive to make a difference. You will be able to thrive in our close-knit, safety-focused culture working together as ONE TEAM. The careers we offer are meaningful because the work we do matters. Join us! 

Job Summary 

This opportunity plays a critical role in CN's Core Modernization program, which is focused on replacing aging Mainframe-based platforms that support missioncritical railway operations including train operations, yard management, and safety-related systems. 

The Specialist Software Development - Critical Systems SME is a senior technical contributor who brings deep knowledge of legacy systems while actively supporting CN's transition to modern architectures. The role balances hands-on development and support of existing Mainframe applications with strategic modernization activities executed in collaboration with architecture teams and system integration partners. 

This position is ideal for employees with strong legacy expertise who want to contribute their institutional knowledge to a multi-year transformation initiative while ensuring operational stability, regulatory compliance, and safety. 

Key Responsibilities 

• Provide subject matter expertise for critical legacy Mainframe applications supporting railway operations. 

• Design, develop, and implement enhancements to existing Mainframe systems to support regulatory requirements, safety initiatives, and business-driven enhancements. 

• Serve as an escalation point for Application Managed Service (AMS) teams by analyzing complex incidents, defects, and performance issues. 

• Participate in As-Is and To-Be workshops to document and explain legacy system behavior, business rules, integrations, and data flows. 

• Conduct or validate reverse engineering activities to uncover undocumented logic, dependencies, and constraints within legacy codebases. 

• Collaborate closely with Architecture, CAST analysis teams, and system integrators to validate modernization assumptions, modularization approaches, and migration readiness. 

• Attend solution and design workshops to ensure proposed solutions fully and accurately reflect legacy capabilities and operational requirements. 

• Review and validate functional and technical specifications for both legacy enhancements and modernization deliverables. 

• Contribute to Agile sprint planning by identifying cross-system dependencies, technical risks, and story complexity. 

• Provide input into test strategy, test scenario creation, mock data, and conversion activities. 

• Execute and support unit testing, integration testing, regression testing, and performance testing. 

• Support business users during User Acceptance Testing (UAT) and participate in sprint demos and retrospectives. 

• Participate in deployment and Hypercare activities by supporting defect triage, root-cause analysis, and system stabilization. 

Required Skills & Experience 

• Strong functional analysis and functional design experience in complex enterprise or legacy environments. 

• Solid hands-on development experience using Java and C/C++. 

• Proven experience working in Mainframe environments including COBOL and/or Natural/Adabas (asset). 

• Strong understanding of batch processing concepts including JCL, VSAM, Syncsort, and enterprise job schedulers. 

• Experience with IBM Mainframe platforms (e.g., OS/MVS) and supporting tooling. 

• Strong SQL skills with DB2 including analysis and troubleshooting using tools such as Data Studio. 

• Experience working with MQ-based messaging and transactions. 

• Familiarity with integration technologies such as EDI and webMethods. 

• Working knowledge of modern technology stacks such as Microservices, Data Hubs, and event-driven platforms (Kafka). 

What We're Looking For 

• A candidate with railroad knowledge and willing to develop deep knowledge of CN legacy systems and a strong understanding of railway operations 

• A collaborative mindset with the ability to communicate technical concepts clearly to both technical and non-technical stakeholders. 

• Strong analytical, troubleshooting, and documentation skills. 

• Comfort working in Agile delivery environments and large transformation programs. 

• A commitment to system reliability, safety, and operational excellence.

About CN 
CN is a world-class transportation leader and trade-enabler. Essential to the economy, to the customers, and to the communities it serves, CN safely transports more than 300 million tons of natural resources, manufactured products, and finished goods throughout North America every year. As the only railroad connecting Canada's Eastern and Western coasts with the Southern tip of the U.S. through a 19,500 mile rail network,CN and its affiliates have been contributing to community prosperity and sustainable trade since 1919. CN is committed to programs supporting social responsibility and environmental stewardship. At CN, we work as ONE TEAM, focused on safety, sustainability and our customers, providing operational and supply chain excellence to deliver results