Senior Developer

Senior Developer

Are you ready for your next career challenge? Role overview: Provide hands‑on technical leadership for the design, development, integration and support of ESCS software capabilities. The Senior Developer establishes engineering patterns, leads complex implementation work and mentors developers while maintaining a strong focus on security, quality and operability.

The role you will play

Lead software design and delivery within a capability team. Translate architecture and requirements into maintainable engineering solutions. Raise engineering quality through standards, reviews, automation and mentoring.

Primary responsibilities

• Design, build, test and maintain cloud‑based applications, services and integrations.
• Define and apply patterns for APIs, microservices, event‑driven integration and data exchange.
• Lead code reviews, technical design reviews and complex defect resolution.
• Embed secure coding, automated testing, observability and operational readiness.
• Contribute to CI/CD pipelines, infrastructure automation and release practices.
• Create clear technical design and support documentation.
• Estimate work, identify technical risk and collaborate with architecture, analysis, data, test and infrastructure colleagues.
• Mentor developers and support consistent engineering practices across teams.

Required skills and capabilities

• Strong capability in relevant languages and frameworks such as C#/.NET, Java and/or Python RESTful API and integration development
• Microservices and event‑driven architecture
• Cloud‑native engineering on Azure and/or AWS
• Secure coding and software assurance
• Automated unit, integration and component testing
• CI/CD, Git workflows and DevSecOps practices
• Observability, logging, monitoring and diagnostics
• Infrastructure as Code awareness, including Terraform or equivalent
• Technical design documentation and mentoring

Required experience

• Delivery of production software in complex enterprise environments.
• Hands‑on experience of cloud services, APIs, automated build and deployment pipelines.
• Experience leading technical implementation, code quality and engineering decisions.
• Experience integrating with third‑party or SaaS platforms.

Desired experience

• High‑volume transactional or supply chain systems.
• SaaS customisation, extension and integration.
• Containers and orchestration platforms.
• AI‑assisted development used within approved engineering and security controls.

Success in the role

• Software is secure, testable, observable and maintainable.
• Design decisions and interfaces are clearly documented.
• Engineering risks are surfaced early and resolved collaboratively.
• Developers receive practical technical guidance and constructive review.

Clearance Requirements

SC required to start, SC required for the role Leidos UK

Leidos UK

Join our team and discover a culture of collaboration, innovation, diversity, trust, caring management, communication transparency, work‑life balance, and overall job satisfaction.

What we do for you

At Leidos we are PASSIONATE about customer success, UNITED as a team and INSPIRED to make a difference. We offer meaningful and engaging careers, a collaborative culture, and support for your career goals, all while nurturing a healthy work‑life balance.

Our reward scheme includes

• Contributory Pension Scheme
• Private Medical Insurance
• 33 days Annual Leave (including public and privilege holidays)
• Access to Flexible benefits (including life assurance, health schemes, gym memberships, annual buy and sell holidays and a cycle to work scheme)
• Flexible Working Scheme

Commitment to Diversity

We welcome applications from every part of the community and are committed to a truly diverse and inclusive culture. We foster a sense of belonging, welcoming all perspectives and contributions, and providing equal access to opportunities and resources for everyone. If you have a disability or need any reasonable adjustments during the application and selection stages please let us know, and we will respond in a way that best fits your needs.

Who We Are

Leidos UK & EUROPE - we work to make the world safer, healthier, and more efficient through technology, engineering and science. Leidos is a growing company delivering innovative technology and solutions focused on safeguarding critical capabilities and transformation in frontline services, our work in the United Kingdom includes addressing some of the most complex problems in defence, healthcare, government, safety and security, and transportation.

What Makes Us Different

Purpose: you can use your passion and abilities at Leidos to keep the people you care about safe. We are at the forefront of machine learning, AI, cyber security and solutions. Using your skills in the technology frontline by helping to build a safer world. You can inspire change. Collaboration: having flexibility to do your job is one of our core benefits, enabling you to become part of our extraordinary team. We have been empowering our people to work flexibly for years. Whether you work from home, the office or on customer sites, we will give you the digital tools and the flexibility to work smarter and align your needs and ours. People: Leidos empowers people from every background to be themselves and gives you the tools to learn new skills by enabling growth whilst developing . We believe that extraordinary people need opportunities to grow, to be inspired and to inspire others. At Leidos, we invest in technical academies, career rotations and a career development plans that enhance your future. If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo - because the mission demands it. We’re not hiring followers. We’re recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 - and moving faster than anyone else dares.

Pay Range

The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.