Principal Software Engineer – Mission-Critical Platforms (Java/React)
📍 On-Site | 💷 Salary Competitive
🧳 Relocation Assistance Available | UK Citizenship Required
🔐 Must Hold UK-Highest Level Security Clearance
Lead a team delivering secure, high-impact software solutions for national defence.
My client is seeking a Principal Software Engineer to oversee the design, development, and delivery of complex software systems across defence, security, and intelligence domains. You’ll combine hands-on engineering with technical leadership, guiding a multidisciplinary team through agile delivery while maintaining technical excellence.
This is a leadership role for someone passionate about building stable, elegant solutions in a mission-critical environment, with the autonomy and backing to make meaningful decisions that impact national security.
🔧 What You’ll Do:
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Own team deliverables, working alongside the Scrum Master to meet mission and delivery goals
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Lead technical design, code development, testing and deployment of secure, scalable systems
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Guide and mentor junior developers, setting engineering standards and fostering growth
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Collaborate with front-end engineers, DevOps, and QA teams to integrate full-stack solutions
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Engage directly with stakeholders to shape outcomes based on real-world needs
✅ What You’ll Bring:
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Hands-on experience as a Senior or Lead Software Engineer
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Specialism in backend Java (Spring Boot, Maven) or frontend React (Node, npm)
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Proven record designing and deploying robust systems in secure environments
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Familiarity with CI/CD, containerisation, and cloud-native tools: Jenkins, Docker, Kubernetes, AWS
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Strong collaboration, communication, and Agile working practices
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UK highest level of government clearance (active and current)
🧭 Why Join?
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A mission-driven team solving the most complex engineering challenges in defence and intelligence
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9-day fortnight available (every other Friday off)
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Private healthcare, bonus schemes, career pathways
Inclusive environment with leadership who invest in your development