Freelancer profile translated to English.
Back to original languageAbout Nicolas
- Java backend difficult to scale?
* Slow, fragile, or costly-to-maintain API?
I help teams refactor or evolve their Java / Spring Boot backend to make it more robust, performant, and, above all, easier to scale over time.
I specialize in:
• Refactoring Java / Spring Boot backends
• Designing and evolving REST APIs
• Improving code quality and testing
• Modularizing overly coupled architectures
• Optimizing backend performance
When needed, I also work at the backend/interface boundary to efficiently connect APIs, web, and mobile (React / React Native).
Example projects:
• Creating APIs for mobile applications
• Refactoring a hard-to-maintain backend
• Improving the performance of a critical service
• Preparing a more scalable architecture
Main Stack:
Java • Spring Boot • REST APIs • SQL • React • React Native
The objective always remains the same:
design a system that is more reliable today and simpler to evolve tomorrow.
Available to discuss your project.
French
Native or bilingual
English
Fluent
Remote only
Primarily works remotely
Experience
- InpulseCreatorFebruary 2026 - March 2026 (1 month)InPulse— Collective signal capture application (Java / Spring Boot / React Native)ContextDeveloping a product to capture a simple and actionable collective signal from short questionnaires. The goal is to produce a clear indicator to quickly align an organization (HR, community, event) without generating informational noise or collecting personal data.The system is intentionally designed around strong principles:
- Credible anonymity
- Ease of use
- No user accounts
- Collective signal rather than individual data
BackendDesigning a backend for capturing and calculating the collective signal.Main features:InPulse creation and configuration (questions, anonymity threshold, tokens)Anonymous participation via unique tokenPrevention of multiple responsesAccess to the collective signal only after completionParticipation statisticsSecure administrator endpointsBackend Architecture:- Java 21
- Spring Boot
- Hexagonal architecture
- Use-case driven design
- Separation of Command / Query + Handlers
- Abstract repositories
- In-memory persistence (MVP)
Quality:- Systematic TDD
- Unit tests
- E2E scripts for full flow validation
Mobile ApplicationDeveloping a mobile application to participate in an InPulse in seconds.UX Principles:no user accountdirect opening via QR code or Universal Linksimplified single-screen flowdisplay of the collective signal as soon as it becomes availableFrontend Architecture:- React Native
- Redux
- ViewModel orchestrating use-cases
- Clear and predictable state management
- Lifecycle-aware polling
- Secure storage of participation handle
Product Architectureimpossibility of correlating responses between individualsbackend MVP completed.functional mobile application - FragmentsCreatorSeptember 2025 - January 2026 (4 months)Fragments— Full-stack refactoring of a microservices architecture to a modular monolith (Java / Spring Boot / React Native)Developing a mobile application for discovering and sharing specialty coffees. A detailed technical documentation of the project is available: * The project was initially designed with a microservices architecture, then completely refactored to a modular monolith architecture to reduce technical complexity while maintaining a strong business domain separation.**On the backend**, the application was re-imagined around several business contexts (authentication, coffees, social, tickets, articles), with an organization inspired by DDD, separation of read/write concerns, explicit use cases, ports/adapters, and event-driven internal communication.The system also relies on a shared kernel integrating CommandBus, QueryBus, EventBus, as well as an outbox pattern to reliably broadcast events to Kafka and WebSockets.**On the frontend**, the React Native mobile application was structured to align with the domain and backend: organization by features, separation of adapters/core logic/view models/gateways, state management with Redux, synchronization logic, client-side outbox, and WebSocket ACKs.The project places significant importance on software quality with a comprehensive testing strategy: unit tests, integration tests, end-to-end tests, and the use of Testcontainers to validate flows under realistic conditions.This refactoring resulted in a more readable, maintainable architecture that better aligns with the actual product needs.Stack: Java, Spring Boot, React Native, Redux, DDD, CQRS, Event-Driven Architecture, Kafka, WebSocket, Testcontainers, REST APIs.
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Education
- Training TDD, Clean Architecture and DDD in the Java worldWealcome2025Test-Driven Development (TDD) Domain-Driven Design (DDD) Clean / Hexagonal Architecture Réalisation complète d'un backend Java réaliste, en live coding avancé, basé sur un cas métier digne de ce que l'on rencontre en entreprise — loin des katas simplistes.
- Training TDD and Clean Architecture in the Web world with React, Typescript, State ManagerWealcome2025Le Test-Driven Development (TDD) - La Clean / Hexagonal Architecture Réalisation complète d'un FrontEnd React réaliste, en live coding avancé, basé sur un cas métier digne de ce que l'on rencontre en entreprise — loin des katas simplistes.