HCI Software Engineer

SII Group delivers Digital Services, IT, Engineering, and Consulting to diverse industries, enabling digital transformation through our commitment to Growth, People, and CSR.

With over 16,000 professionals across 21 countries, we’re recognised as a “Great Place to Work” for fostering a high-trust culture. Our core values of Trust, Commitment, Accountability, Passion, Creativity, and Transparency drive our work package delivery, ensuring we meet and exceed client expectations as a committed partner.

Since 2016, SII UK has supported top Aerospace & Defence, Aviation, Transportation, and Finance clients, empowering digital transformation with industry-leading engineering expertise. Let’s Tech Together is our promise to encourage innovation and teamwork. We support our engineers with development opportunities and a collaborative, inclusive environment where every voice is valued and empowered.

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THE OPPORTUNITY

We’re looking for a collaborative and experienced software engineer to join a dynamic team developing high-performance, user-focused applications in a secure environment. This is an opportunity to work on impactful systems that support real-world operations, in a setting that values knowledge sharing, clean code practices, and professional growth. You’ll be surrounded by people who take pride in their work, support one another, and are committed to delivering quality software solutions. This is a role where your technical expertise will make a difference — and where your ideas and mentorship can help shape the team and the product.

EXPERIENCE AND SKILLS:

Software Engineer – Secure Systems

What you’ll bring to the team:

• Ability to obtain SC Clearance with no caveats, or already in possession of this

• Ability to work onsite 5 days a week

• Minimum of 5 years’ experience in software engineering, ideally in complex or high-integrity systems • Advanced knowledge of Java and familiarity with Java-based frameworks

• Experience developing intuitive and accessible Human Computer Interfaces

• Hands-on experience with JavaFX, Swing UI, and Spring

• Familiarity with Gradle and/or Maven for build and dependency management

•Proficiency in developing high-performance applications for Linux environments

• Practical experience with Unit Testing (e.g. JUnit) and a commitment to code quality

• Understanding of Static Analysis and Performance Analysis; experience with tools like SonarQube is a plus

• Strong analytical thinking and debugging abilities; experience identifying and resolving performance issues or concurrency challenges

• Commitment to clean, maintainable code — including experience with refactoring, following coding standards, and using design patterns

• Excellent communication skills — both written and verbal — for collaborating effectively and documenting systems clearly

• Strong experience with software architecture and design documentation

• Practical knowledge of version control and software configuration management, especially using Atlassian tools (e.g., Jira, Confluence, Bitbucket/Git)

• A collaborative mindset with a willingness to mentor junior team members and contribute to a positive team culture.

Bonus Experience (Desirable but not required):

• Familiarity with UML and tools like Rational Rhapsody

• Experience using Requirements Management tools such as DOORS or Polarion

• Exposure to Agile ways of working and self-organising teams

• Understanding of virtualisation and containerisation technologies

• Knowledge of IP networking protocols

• Familiarity with CI/CD pipelines and tools like Jenkins and JFROG Artifactory

• Experience aligning requirements and testing within integrated systems .

Why join us? You’ll be part of a supportive, high-performing team where your contributions are valued. We believe in continuous learning, thoughtful collaboration, and building software that serves its users effectively and responsibly. Whether you’re mentoring others or growing your own skills, we’ll help you thrive. Think you meet some but not all the criteria? Please feel free to still apply and we can take your CV in to consideration.

BENEFITS:

• Competitive Basic Salary
• 6% Employers Contribution + 6% as a salary sacrifice
• Private Medical Insurance, Life Cover and Income Protection
• 25 days holiday
• 5 days full sick pay per year
• Cycle to Work & TechScheme
• Corporate access to the Udemy platform

* If you\’re applying for a role requiring security clearance, please be aware that foreign or dual nationality is not an automatic bar, however certain posts may have restrictions which could affect those who do not have sole British nationality or who have personal connections with certain countries outside the UK.

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