C# / .Net Developer

Experis UK; Luton; Hybrid; GBP 65,000 - 90,000; Full time

Job summary

Experis UK is seeking an experienced Senior Software Engineer to join a high-calibre team developing next-generation defence software in Luton. You will own meaningful technical challenges across the software lifecycle, delivering robust C#/.NET solutions for mission-critical systems.

You’ll work in a mature engineering environment that values clean architecture, automated testing and high-quality delivery, with 12-month contract and a strong extension likelihood.

Qualifications

• Strong commercial experience with C# and .NET.
• Experience delivering production software across the full SDLC.
• Solid understanding of software architecture and design principles.
• Experience building testable, maintainable code.
• Knowledge of automated testing and CI/CD practices.
• Experience working within collaborative Agile teams.
• The confidence to operate independently and take ownership of delivery.

Responsibilities

• Designing and building robust applications using C# and .NET.
• Developing scalable software within complex mission-critical environments.
• Working closely with systems, software and integration engineers.
• Contributing to architecture and technical decision-making.
• Implementing automated testing and quality engineering practices.
• Supporting software through integration, validation and deployment.
• Delivering maintainable, secure and high-performance solutions.

Skills

C#

.NET

Automated Testing

CI/CD

Agile Delivery

Windows

Job description

12-Month Contract | Luton (4 Days Onsite, 1 Day Remote) | Inside IR35

Build technology that genuinely matters.

Most software powers businesses.

This software helps protect them.

We're looking for an experienced C# .NET Engineer to join a highly capable team developing next-generation electronic warfare and mission systems used in some of the UK's most advanced defence programmes.

You'll be working on complex, real-world engineering challenges where performance, reliability and quality are critical. This is not greenfield startup experimentation or routine business applications. It's software that operates in demanding environments where failure isn't an option.

You'll join a mature engineering organisation where strong technical practices, clean architecture and high-quality delivery are genuinely valued.

What You'll Be Doing

As a Senior Software Engineer, you'll take ownership of meaningful technical challenges throughout the software development lifecycle.

You'll be:

• Designing and building robust applications using C# and .NET
• Developing scalable software within complex mission-critical environments
• Working closely with systems, software and integration engineers
• Contributing to architecture and technical decision-making
• Implementing automated testing and quality engineering practices
• Supporting software through integration, validation and deployment
• Delivering maintainable, secure and high-performance solutions

This role offers a high degree of autonomy, trust and technical ownership.

The Technology

You'll be working within a modern engineering environment that includes:

• C#
• .NET
• Automated Testing
• Object-Oriented Design
• Agile Delivery (Scrum / Kanban)
• Windows-Based Systems

What We're Looking For

We're interested in engineers who enjoy solving difficult technical problems and writing software properly.

You'll likely have:

• Strong commercial experience with C# and .NET
• Experience delivering production software across the full SDLC
• A solid understanding of software architecture and design principles
• Experience building testable, maintainable code
• Knowledge of automated testing and CI/CD practices
• Experience working within collaborative Agile teams
• The confidence to operate independently and take ownership of delivery

Most importantly, you'll care about engineering quality.

Why This Opportunity?

Meaningful Work

Develop software that supports some of the UK's most sophisticated defence and electronic warfare capabilities.

Long-Term Programme

12-month engagement with strong likelihood of extension.

Technical Challenge

Complex systems, interesting problems and engineering at scale.

Work alongside experienced software, systems and mission engineers.

Stability and Impact

Due to the nature of the work, active UK SC Clearance is essential and must be held prior to application.