Freelancer profile translated to English.

Description

Java Spring Backend Developer | Tech Lead & Application Architect

Is your backend application held back bydifficult-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 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 good development practices. I handle **code reviews**, technical team supervision, 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 versions of Java / Spring Boot

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 7 months)
Paris, France
→ Mission Objective:
Serve as Tech Lead to guide a development team, stabilize the application, and support technical and functional evolutions.

→ Achievements:

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

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

Implemented technical optimizations (Java, Spring Boot, PostgreSQL/PostGIS) leading to performance gains and improved 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 monitoring 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 Java backend processing performance and strengthen software development and delivery practices.

→ Achievements:

Drastically reduced execution time for Java Spring backend batch processes (from 2 hours to 2 minutes), improving performance, scalability, and user satisfaction.

Optimized CI/CD pipeline and audited development practices, resulting in time savings and improved perceived quality of deliveries.

Provided Tech Lead support in Java Spring for 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

Frédéric

Responsable applicatif - GRDF - DSI - SIRED

Less than 1 year project

Reviewed on 12/8/2025

Yann has been the Tech Lead for our Java application for a year. He transformed our monolith into a modular architecture and designed a resilient solution that has sustained our production processes. He also mentored and upskilled the team's developers. Beyond technical expertise, he challenges functional requests to propose more robust and value-creating solutions. An ideal profile for missions where the ability to transform complex existing systems is essential.

Jonathan

BACCARAT

Reviewed on 10/15/2025

Yann did a remarkable job on a complex and technical mission. His ability to recover our old program sources and create a functional compilation environment demonstrates high-level expertise. He showed proactivity, professionalism, and great efficiency. We highly recommend him for technical and demanding projects.

Show all 4 reviews