Senior Software Engineer

X4 Life Sciences; Paris; Hybrid; EUR 90,000 - 150,000; Full time

Job summary

X4 Life Sciences seeks a Freelance Senior C++ Application / Solution Architect to lead a long-term project for a major French energy-sector client. You will own the architecture, drive modernization toward a microservices approach, and mentor teams across architecture committees.

The role requires 10+ years in C++, strong STL/Boost/OOP, UML/ArchiMate, and experience with REST/gRPC/Kafka. Paris-based client site with occasional remote work, and a fast interview process.

Qualifications

• 10+ years of hands-on C++ development, with strong command of C++17 (ideally C++20)
• Solid knowledge of STL, Boost, and OOP, SOLID and design patterns
• Experience with Qt and QML (Drogon is a plus)
• 2+ years as an Application / Solution Architect
• Proven experience designing microservices and distributed systems, including event-driven architectures
• Knowledge of REST, gRPC and Kafka
• Experience with DDD, TDD and BDD
• Strong UML skills; ArchiMate is highly desirable
• Tooling: CMake, Conan, Qt ecosystem

Responsibilities

• Define the target application architecture (microservices and/or modular)
• Design services and the communication between them
• Analyse the existing architecture and drive its modernization
• Contribute to the technical foundation/framework, reusable libraries and project templates
• Model architectures with ArchiMate and UML, and produce architecture and design documentation
• Support developers through code reviews and promote SOLID principles and design patterns
• Lead technical workshops and training sessions, and prepare material for architecture committees
• Take part in technology selection and technical watch

Skills

C++ development

SOLID & patterns

UML & ArchiMate

REST & gRPC

Kafka

DDD/TDD/BDD

Tools

CMake

Conan

Qt

QML

Drogon

ArchiMate

Job description

Freelance Senior C++ Application / Solution Architect | France | Immediate Start

We're looking for a genuinely senior C++ architect for a long-term assignment with a major French energy-sector client. You'll join an architecture team of around 12 people and take ownership of an application perimeter made up of several existing software components, with a strong focus on redesigning it into a microservices architecture running on Kubernetes.

What you'll do

• Define the target application architecture (microservices and/or modular)
• Design services and the communication between them
• Analyse the existing architecture and drive its modernization
• Contribute to the technical foundation/framework, reusable libraries and project templates
• Model architectures with ArchiMate and UML, and produce architecture and design documentation
• Support developers through code reviews and promote SOLID principles and design patterns
• Lead technical workshops and training sessions, and prepare material for architecture committees
• Take part in technology selection and technical watch

What we're looking for

• 10+ years of hands-on C++ development, with strong command of C++17 (ideally C++20)
• Solid knowledge of STL, Boost, and OOP, SOLID and design patterns
• Experience with Qt and QML (Drogon is a plus)
• 2+ years as an Application / Solution Architect
• Proven experience designing microservices and distributed systems, including event-driven architectures
• Knowledge of REST, gRPC and Kafka
• Experience with DDD, TDD and BDD
• Strong UML skills; ArchiMate is highly desirable
• Tooling: CMake, Conan, Qt ecosystem

Proactivity, ownership, autonomy, problem-solving, team spirit, and the ability to explain complex topics clearly and coach developers, both orally and in writing.

Good to know

• Client site in Paris, France, with 1–2 days of remote work per week possible
• Ideally 100% allocation
• Quick interview process - technically demanding