Senior Java Software Engineer

Senior Backend Engineer — Java / Spring Boot / AWS £80,000–£120,000 | Permanent | Hybrid – Warminster area, 3 days onsite I'm partnering with a global software product business delivering mission-critical platforms across defence, government and resilience. They're expanding the engineering team behind a major, multi-year UK defence programme and are looking for a Senior Backend Engineer who wants more than another maintenance-heavy Java role. This is an opportunity to work on complex, production-grade systems where reliability, scalability and engineering quality genuinely matter, with real ownership over architecture, technical decisions and how the platform evolves. What you'll be working on You'll design, build and evolve backend services within a modern distributed architecture, working closely with experienced engineers, technical leads and product stakeholders. The environment includes:

• Java 17+ / Java 21
• Spring Boot
• REST APIs
• PostgreSQL
• Kafka / event-driven architectures
• AWS
• Docker & Kubernetes
• CI/CD
• JUnit / Mockito / TDD
• Microservices and distributed systems You won't simply be handed tickets. You'll be expected to contribute to system design, challenge technical decisions, improve engineering standards and take ownership of software from design through to production. What they're looking for You'll likely have strong commercial experience building backend systems with Java and Spring Boot, alongside good knowledge of APIs, databases and distributed architectures. They're particularly interested in engineers who can demonstrate experience with:
• Building production Java / Spring Boot services
• Microservices or distributed systems
• REST API design
• PostgreSQL or similar relational databases
• AWS or another major cloud platform
• Docker / Kubernetes
• Messaging technologies such as Kafka or RabbitMQ
• Automated testing and clean engineering practices
• Code reviews and technical design discussions Experience within defence, aerospace, government, fintech, healthcare or another highly regulated / mission-critical environment would be useful, but isn't essential. Why it's interesting The attraction here is the level of technical ownership. You'll be joining a programme with long-term investment behind it, working on software that has genuine operational importance rather than another short-lived internal application. There is also scope to influence:
• Architecture and system design
• Engineering standards
• Technical debt reduction
• Reliability and scalability
• Development practices
• Future technical direction For engineers looking to progress towards Staff / Technical Lead level, there is plenty of room to increase your influence while remaining hands-on. Package Salary: up to approximately £120,000, depending on experience Contract: Permanent Location: Warminster area Hybrid: approximately 3 days per week onsite Due to the nature of the programme, candidates will need to hold or be eligible to obtain UK security clearance. If you're an experienced Java engineer looking for technically challenging work, meaningful ownership and the chance to contribute to a major long-term programme, I'd be very interested in speaking with you.