Senior .NET Developer

Senior Consultant - .NET Developer (Security Clearance) - Luxembourg

Adservio Luxembourg · Luxembourg, Luxembourg · Full-time · Posted 2026-09-21

Workplace: on_site

Department: Dev

Description

dservio Luxembourg
Adservio Luxembourg is the Luxembourg arm of Adservio Group — 300+ consultants across Paris, Brussels and Luxembourg, 15 years serving regulated industries. We opened in Luxembourg in 2022 and work across financial services, energy and utilities, transport and mobility, insurance and the public sector. You join our Technologies & Engineering team.

The context
With our team, you work for an international organisation in the defence sector, based in Luxembourg. Its business applications support critical logistics and operations in a security-classified environment, where availability, traceability and information security are not negotiable. The role is full-time on-site and requires a security clearance.

Your mission
You design, build and run business applications that people rely on every day, in an environment where every change is controlled.

Build and evolve

• Develop new features and improve existing applications, from technical design to delivery
• Write maintainable, tested code that complies with the organisation's security standards

Run and secure

• Analyse and fix production incidents with the operations teams
• Apply the security and change-management rules specific to classified environments

Work with the business

• Turn functional needs from business analysts and project managers into technical solutions
• Document your work so that it can be audited and handed over

Your profile
What is essential

• At least 5 years of hands-on development with C# and the .NET ecosystem
• A valid NATO SECRET security clearance, or a dormant clearance that can be reactivated
• Solid experience with SQL Server: data modelling, queries, performance
• A degree in computer science or software engineering

What makes the difference

• Previous work for an international organisation or in a defence environment
• Experience with Docker and CI/CD pipelines
• A front-end framework (Angular or React)

Languages
Required: fluent professional English · Asset: French, German or any other language

What you find with us
A tribe. You join our development tribe: senior peers, peer reviews and shared technology watch.
Recognised expertise. Subject Matter Expert is a real status with us: other consultants and group clients come to our experts.
Regulated environments, across sectors. Your work sits where compliance is not optional and failure is not acceptable. The methods you apply here carry over to our work in energy, transport, insurance and the public sector.
A practice still being built, with a clear path. Our Luxembourg office opened in 2022 and is backed by a group of 300+ consultants: what you help set up becomes the way we work. Our grade framework is explicit, with an expert track if you prefer depth over management.

The process
Application → HR conversation → Technical interview with your future peers → Feedback and decision. Whatever the outcome, you will get an answer.

Apply

Apply at Adservio Luxembourg

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