Software Engineer - London

About The Role

FDM is a global business and technology consultancy seeking a Software Engineer to support our client within the Defence and Secure Technology sector. This is an initial 6‑month contract with potential to extend, offered on a hybrid basis in London with two days per week onsite. Candidates must be eligible for UK security clearance (or already hold clearance).

The role will support a new secure innovation project focused on early-stage R&D and rapid prototyping. The role will contribute to the delivery of a Technology Readiness Level 3 proof of concept, demonstrating how security-first engineering and emerging technologies such as AI can enhance collaboration and information sharing in high-trust, defence-aligned environments.

This opportunity is well suited to engineers who enjoy experimentation, fast iteration, and working in environments where requirements evolve.

Responsibilities

• Design and build rapid proof-of-concept applications within a secure development environment.
• Develop user-focused solutions with a strong emphasis on usability, user experience, and rapid iteration.
• Contribute to the enhancement and extension of an existing .NET-based platform and distributed computing architecture.
• Apply distributed computing principles to build scalable, resilient, and secure solutions.
• Integrate AI and machine learning capabilities into prototype applications, including the selection, evaluation, and implementation of appropriate models.
• Collaborate with technical architects and engineering teams to align new capabilities with existing platform architecture.
• Apply security-first engineering principles to collaboration and information-sharing challenges.
• Produce maintainable, well-structured code and supporting technical documentation.
• Work closely with engineers, security specialists, and product stakeholders throughout the prototyping lifecycle.

About You

• Minimum of 5 years' experience in software engineering, R&D, or prototyping-focused roles.
• Strong experience developing applications within the Microsoft .NET ecosystem, including modern C# development.
• Experience working with distributed systems, distributed computing concepts, or actor-based architectures.
• Proven track record of delivering rapid prototypes, proofs of concept, or innovation-focused software solutions.
• Strong appreciation for user-centred design and building intuitive user experiences.
• Experience integrating AI, machine learning, or advanced analytics capabilities into software applications.
• Ability to evaluate, select, and integrate appropriate AI models, including large language models and related technologies.
• Understanding of software architecture, systems design, and modern development practices.
• Experience working within secure, restricted, regulated, or defence-aligned environments is advantageous.
• Ability to operate effectively in ambiguous environments where requirements evolve rapidly.
• Eligibility for UK Security Clearance or the ability to obtain clearance.

Desirable Experience

• Competent in a .NET ecosystem and with distributed computing concepts
• Experience working with AI frameworks, LLM integrations, and model orchestration tools.
• Exposure to cloud-native architectures and secure deployment environments.
• Experience supporting research, innovation, or experimental technology programmes.
• Experience developing solutions for defence, national security, or highly regulated sectors.

About Us

FDM is an award-winning global leader in tech and business talent solutions, backed by more than 35 years of industry experience. We have centres across Europe, North America, and Asia-Pacific, and a global workforce of over 2500 employees.

FDM has shown exponential growth throughout the years, firmly establishing itself as an award-winning employer, currently listed on the FTSE4Good Index and as a 2026 Financial Times UK ‘Best Employer’.

Diversity and Inclusion

FDM Group is an equal opportunity employer, and all qualified applicants will receive consideration for employment without regard to race, colour, religion, sex, sexual orientation, national origin, age, disability, veteran status or any other status protected by federal, provincial or local laws.

Why join us

• Career coaching, mentoring and access to upskilling throughout your entire FDM career
• Assignments with global companies and opportunities to work abroad
• Opportunity to re-skill and up-skill into new areas, develop non-linear career paths and build a skillset within your field
• Annual leave and work-place pension