Senior C++ Developer (Principal)

About the role

Atos is seeking a Principal C++ Developer to join its Air Traffic Management team in Brussels. The role focuses on designing and building high‑performance, mission‑critical software that operates under real‑world pressure. The position is initially a freelance contract with the possibility of a permanent offer for the right candidate.

Key responsibilities

• Lead the technical design and architecture of complex C++ systems.
• Develop, optimise and maintain high‑throughput, low‑latency code using modern C++ standards.
• Collaborate with cross‑functional teams to integrate databases and REST APIs.
• Implement and maintain build pipelines (CMake/Make) and CI/CD workflows.
• Conduct performance tuning, secure coding reviews and unit testing.

Required profile

• Minimum 8 years of hands‑on C++ development experience.
• Strong expertise in modern C++ (C++11/14/17/20), STL and Boost.
• Deep understanding of multithreading, memory management and template metaprogramming.
• Experience with system architecture, performance optimisation and secure coding practices.
• Proficiency with build systems, debugging tools and CI/CD pipelines.

Required skills

• C++ (C++11/14/17/20)
• STL, Boost
• Multithreading, memory management, templates
• CMake, Make
• Google Test, Catch2
• REST APIs, database integration
• CI/CD, debugging tools

What we offer

• Competitive freelance contract for up to 9 years with renewal options.
• Hybrid work model: three days onsite in Brussels‑Haren.
• Opportunity to influence architecture of safety‑critical aviation software.
• Potential transition to a permanent position.