Senior Software Engineer - Mission-Critical Systems

CGI was recognised in the Sunday Times Best Places to Work List 2025 and has been named one of the ‘World’s Best Employers’ by Forbes magazine. We offer a competitive salary, excellent pension, private healthcare, plus a share scheme (3.5% + 3.5% matching) which makes you a CGI partner not just an employee. We are committed to inclusivity, building a genuinely diverse community of tech talent and inspiring everyone to pursue careers in our sector.

CGI’s Space, Defence and Intelligence business unit focuses primarily on the delivery of contemporary and innovative technical solutions for the government agencies' most challenging problems. We work, build, and operate bespoke, technically complex, mission‑critical systems which help our clients keep us all safe and secure. We are currently looking for experienced software engineers to join our cross‑functional team who, in partnership with our clients, will help define, guide and assure the delivery of integrated solutions. The role offers fantastic opportunities to work within an interesting and highly rewarding environment.

We are heavily committed to developing our members and provide excellent learning and development opportunities to ensure that your knowledge and skills keep pace with the evolving technology landscape. We engender a culture of innovation, collaboration and ownership; highly motivated self‑starters thrive within our organisation. Although we would like candidates to have all the skills we need, we would consider high quality individuals who meet most of the criteria.

Due to the secure nature of this project, this role requires candidates to either already hold, or be eligible to obtain, a high level of UK Security Clearance. To meet the eligibility criteria for this clearance, applicants must be sole British nationals, have been resident in the UK for the past 10 years, and must not have spent more than 28 consecutive days outside the UK within the last five years. Individuals who do not currently hold clearance are still encouraged to apply and will be considered both for this position and for other suitable opportunities within CGI where appropriate.

This role is primarily based on a secure client site and requires attendance on site five days per week due to the sensitive nature of the work and the systems involved. While the position is predominantly site‑based, there may be occasional flexibility where business needs and security constraints allow. Any such arrangements would be agreed in advance with the project team.

Your future duties and responsibilities include:

• Contributing to the development of cutting‑edge projects supporting high‑value, mission‑critical operations.
• Working on innovative software projects where your technical decisions will directly influence the performance, resilience, and security of systems used in real‑world operational environments.
• Being involved end‑to‑end in the design, development, and delivery of advanced software capabilities.
• Helping shape and implement new features, optimise existing functionality, and drive improvements that enhance system stability, scalability, and usability.
• Configuring and integrating software components, maintaining complex deployment environments, and supporting changes to live systems to ensure continuous and secure service delivery.
• Collaborating closely with technical experts, architects, and stakeholders to solve challenging problems using innovative and analytical approaches.

We are looking for candidates who are not only strong technically but who bring a proactive, positive problem‑solving attitude, and who can adapt to evolving client needs with professionalism and creativity. You will thrive in this role if you enjoy working on high‑impact solutions that require both precision and imagination.

Required qualifications to be successful in this role include experience in one or more of the following technologies:

• Programming Languages: Java, Python, RUST
• Frontend Frameworks: Vue.js (or similar modern JavaScript frameworks)
• Scripting