Freelancer profile translated to English.

Description

Java Spring Backend Developer | Tech Lead & Application Architect

Is your backend application being held back byhard-to-maintain legacycode, technical debt weighing down your teams, or a need to stabilize the architecture before scaling? I step in as aJava Spring Backend Tech Lead / Architectto put your systems back on solid ground.

I am asenior backend developer specializing in Java and Spring**. My role: to frame the technical aspects of a project, mentor developers, ensure code quality, and guarantee a stable architecture. Depending on your needs, I can work **integrated into your teamsoron a fixed-price basisfor a specific scope (refactoring, modernization, migration, optimization, audit).

Throughout my assignments, I have supported companies on demanding projects: stabilizing existing systems, reducing technical debt, improving performance, and implementing best development practices. I handle **code reviews**, technical team monitoring, restructuring critical features, and optimizing architectures.

On a fixed-price basis, I take charge of key projects:

Refactoring and modernization of legacy code

Migration to recent Java / Spring Boot versions

Backend architecture optimization

Performance and resilience improvement

Technical audit with prioritized action plan

Stack and methods:Java 8, Java 11, Java 17and above, Spring Framework / Spring Boot, Hibernate, JPA, Docker, Kubernetes, continuous integration and deployment (CI/CD, GitLab, Jenkins), relational and NoSQL databases, monitoring and quality tools.

My approach:deliver stable, maintainable solutions aligned with your business objectives.

Let's discuss your context: I offer a quick video call to understand your needs and define a suitable intervention. Response guaranteed within 24 hours.

Industry field of expertise

Languages

French
Native or bilingual
English
Fluent

Workplace preferences

Can work on-site

Paris (up to 50km), Lyon (up to 50km), Marseille (up to 50km), Lille (up to 50km), Bordeaux (up to 50km)

GRDF
Back-End Developer | Tech Lead | Java Spring
ENERGY AND UTILITIES
November 2024 - Today (1 year and 9 months)
Paris, France
→ Mission Objective:
Ensure the role of Tech Lead to guide a development team, stabilize the application, and support technical and functional evolutions.

→ Achievements:

Supervised and coached developers to improve code quality, optimize collaboration, and accelerate skill development.

Evolved the system and application architecture to enhance the performance, reliability, and maintainability of the business application.

Implemented technical optimizations (Java, Spring Boot, PostgreSQL/PostGIS) resulting in performance gains and better production stability.

→ Technical Stack:
Java, Spring Boot, Spring Data JPA, Spring Batch, PostgreSQL, PostGIS
Java Spring boot Java 17
Thalès GTS / Hitachi Rail
Back-End Developer | Tech Lead | Java Spring
TRANSPORTATION
March 2024 - January 2025 (9 months)
Vélizy-Villacoublay, France
→ Mission Objective:
Design and deploy a robust software architecture with a comprehensive monitoring and observability system at the program level.

→ Achievements:

Defined a highly available microservices backend architecture, improving the performance, scalability, and perceived quality of critical applications.

Integrated a centralized observability and monitoring solution (Prometheus, Thanos, Grafana, Mimir), providing real-time visibility and optimized tracking of software components.

Led as a Java Spring Boot software architect, ensuring a reliable event-driven architecture and significant time savings in incident analysis and resolution.

→ Technical Stack:
Java, Spring Boot, Microservices, Event-Driven Architecture, Prometheus, Thanos, Grafana, Mimir
Java Docker java audit tech lead java Spring boot
AMUNDI
Back-End Developer | Tech Lead | Java Spring
BANKING AND INSURANCE
January 2024 - February 2024 (2 months)
Paris, France
→ Mission Objective:
Optimize the performance of Java backend processes and strengthen software development and delivery practices.

→ Achievements:

Drastically reduced the execution time of Java Spring backend batch processes (from 2h to 2min), improving performance, scalability, and user satisfaction.

Optimized the CI/CD pipeline and audited development practices, leading to time savings and improved perceived quality of deliveries.

Provided Tech Lead support for Java Spring on estimations and roadmap planning, ensuring increased visibility and better control over evolutions.

→ Technical Stack:
Java, Spring, Spring Boot, CI/CD, Git, Jenkins
Java Spring Clean Code java audit tech lead java

Check out Yann's experience

Jonathan

Directeur des Systèmes Applicatifs - BACCARAT

Reviewed on 7/6/2026

We entrusted Yann with the critical migration of our applications from an obsolete platform to a new, modern, and clean infrastructure. The objectives were fully met: everything was cleaned up and stabilized. Yann showed great professionalism in his support and exemplary organization. A big thank you to him for his commitment and the clarity of our exchanges. He is a trustworthy consultant whom we recommend without hesitation.

Frédéric

Responsable applicatif - GRDF - DSI - SIRED

Reviewed on 6/9/2026

Yann has been working as Tech Lead on our Java/Spring Boot and Spring Batch platform for gas network optimization and simulation for a year and a half. He works autonomously and shows initiative on subjects relevant to the project: delivery of structuring new business features, leading a fundamental architectural overhaul, and working on the security and robustness of the platform's services. He collaborates easily with the different profiles in the team, anticipates technical difficulties upstream, and delivers quickly. In particular, he implemented custom Clean Code tooling (needs analysis, code generation, code review, automated fixes) which contributed to the team's productivity and brought real benefits to the project. His intervention brought real value to the project, and I recommend working with him without reservation.

Show all 6 reviews