Principal Software Engineer: Mainframe Modernization Architect

Rocket Software; Newbury; On-site; GBP 70,000 - 100,000; Full time

Job summary

Rocket Software in Newbury is seeking a Principal Software Engineer to provide deep technical leadership across COBOL development and Enterprise Server application replatforming products. The ideal candidate will have 10+ years in software engineering, a strong background in mission-critical systems, and expertise with COBOL, PL/I, C, or C++. This hands-on role offers opportunities to influence architecture, drive modernization strategies, and mentor engineers in a collaborative environment focused on technical excellence and operational success.

Qualifications

• 10+ years of professional software engineering experience.
• Deep expertise in systems-level software development.
• Proven track record of building or modernizing enterprise-grade tooling.

Responsibilities

• Architect, design, and implement core components within COBOL development tools.
• Own complex technical domains end-to-end from design through production.
• Collaborate with product management to shape roadmap priorities.

Skills

COBOL

Systems-level software development

Leadership

Debugging low-level performance issues

Tools

Azure

AWS

Job description

Rocket Software in Newbury is seeking a Principal Software Engineer to provide deep technical leadership across COBOL development and Enterprise Server application replatforming products. The ideal candidate will have 10+ years in software engineering, a strong background in mission-critical systems, and expertise with COBOL, PL/I, C, or C++. This hands-on role offers opportunities to influence architecture, drive modernization strategies, and mentor engineers in a collaborative environment focused on technical excellence and operational success.