Principal Software Engineer

Company: Copello
Apply for the Principal Software Engineer
Location: Portsmouth
Job Description:

Overview

In this role you will own the end-to-end software lifecycle for secure, mission-critical products in a defence environment. You’ll lead embedded and/or application software development, shaping architecture with cross-functional teams and mentoring engineers. You will drive robust testing, modern engineering practices, and technical reviews to deliver reliable, scalable solutions. This position offers hands-on impact, technical growth, and the chance to influence secure software at scale.

Pay / Benefits

  • bonus
  • private medical
  • enhanced pension
  • 25 days’ holiday + bank holidays
  • flexible benefits
  • potential early Friday finish

Responsibilities

  • Design and develop embedded and/or application software
  • Use C/C++ across bare-metal, RTOS, and Linux environments
  • Apply Object-Oriented Design and SOLID principles
  • Support software architecture, requirements, and technical design
  • Advocate TDD/BDD, CI, DevSecOps, and automated testing
  • Collaborate with Systems, Hardware and Firmware engineers
  • Lead technical reviews and contribute to engineering decisions
  • Mentor less experienced engineers
  • Contribute to technical proposals, bids, and future product development
  • Drive improvements in software tools, processes, and engineering practices

Key requirements

  • Strong C/C++ experience
  • Significant embedded software development experience
  • Experience with bare-metal, RTOS and/or Embedded Linux
  • Strong understanding of SDLC and best practices
  • Experience with Object-Oriented Design and Design Patterns
  • Strong testing and design-for-test experience
  • Experience in complex or regulated environments
  • Knowledge of Rust, TCP/IP, MISRA, DevSecOps, CI/CD, DOORS, UML, SysML or Enterprise Architect would be advantageous
  • Mentoring and coaching
  • Technical leadership
  • Collaborative cross-functional collaboration
  • C/C++
  • Embedded software development
  • Bare-metal/RTOS/Embedded Linux

Posted: September 14th, 2026