Freelancer profile translated to English.
Back to original languageAbout Julien
Hello, I'm Julien, a mobile developer specializing in Flutter, Kotlin, and Kotlin Multiplatform (KMP).
I help startups, SMEs, and project owners create modern, performant, and maintainable mobile applications, from the idea to the store publication.
What I can handle:
- Flutter iOS & Android app development
- Kotlin Multiplatform (KMP/KMM)
- Scalable mobile architecture
- Firebase / Supabase backend
- Fast and solid startup MVPs
- Redesign or optimization of existing applications
- App Store & Google Play publication
- Payments and subscriptions (Stripe / RevenueCat)
- APIs, generative AI, and automations
- Real-time, push notifications, geolocation
- Mobile UX performance and optimization
My approach:
I don't just "code an app".
My goal is to build a technically viable and business-coherent mobile product:
- Clean and maintainable architecture
- Development speed
- Fluid user experience
- Controlled technical debt
- Preparation for scaling
I'm used to working in startup environments with strong constraints on time, budget, and product iteration.
Main Stack:
Mobile
- Flutter
- Dart
- Kotlin
- Kotlin Multiplatform
- Native Android
Backend & Cloud
- Firebase
- Supabase
- Cloud Functions
- REST APIs
- PostgreSQL
Architecture & Tools
- Riverpod
- Clean Architecture
- Git
- CI/CD
- RevenueCat
- Stripe
- Figma
Why work with me:
- Product and business vision
- Clear and fast communication
- Strong autonomy
- Long-term architectural thinking
- Ability to ship quickly without sacrificing quality
Available for:
- MVPs
- Mobile team reinforcement
- Technical audits
- Application redesigns
- Mobile CTO support
- Long-term missions
Feel free to contact me to discuss your project.
French
Native or bilingual
English
Conversational
Can work on-site
Paris (up to 50km), Paris (up to 50km), Dunkerque (up to 50km)
Experience
- MTP SASCTO & Flutter DeveloperSPORTSJanuary 2025 - Today (1 year and 7 months)Paris, FranceSince January 2025, I've been assisting MTP Running in designing and developing their digital platform dedicated to sports coaching.I developed the mobile application and the back-office from scratch using Flutter, FlutterFlow, and Firebase, designing a scalable architecture to meet the needs of both coaches and athletes.Key accomplishments include:
- Complete development of the mobile application (iOS & Android)
- Development of the administration back-office
- Firebase architecture design (Authentication, Firestore, Cloud Functions, Storage)
- Integration of RevenueCat for subscription management
- Implementation of push notifications
- Development of a messaging system between users and coaches
- Creation of algorithms for automatic assignment of training plans and exercises
- Integration of Strava, Garmin, and COROS APIs
- Synchronization and sending of workouts to compatible smartwatches
- Participation in UX/UI design and creation of mockups on Figma
- Maintenance, continuous evolution, and performance improvement of the platform
This project allowed me to be involved in the entire product development cycle, from design to deployment, working on data synchronization, third-party integrations, scalability, and user experience issues. - Alph4CorporationsFreelanceTECHJanuary 2023 - Today (3 years and 7 months)Paris, FranceFor over two years, I've been assisting startups and companies in developing mobile and web applications, combining performance, design, and optimal user experience.I've had the opportunity to work on a wide variety of projects, ranging from native applications (Kotlin for Android) to cross-platform solutions with Flutter and FlutterFlow.My expertise also covers backend integration and management with Firebase, ensuring scalable and secure applications.Whether for development from scratch, improving an existing application, or specific integration, I apply my skills to deliver high-performance solutions tailored to client needs.
- LINKIZZMobile DeveloperEDUCATION AND E-LEARNINGSeptember 2022 - December 2022 (4 months)Paris, FranceAs part of the development and maintenance of a private social network editor for care facilities (nurseries, micro-nurseries, nursing homes) aimed at connecting field staff and external families:Kidizz Daily Development (B2B Business Tablet Application): Responsible for the finalization and evolving maintenance phases of the tablet application in Kotlin and Jetpack Compose, dedicated to internal use by facilities (complex scheduling management, precise check-in/out, and event tracking).Legacy Code Refactoring (Main Kidizz Application): Supported the existing technical team by completely rewriting the core module for creating, modifying, and fine-tuning polls in Java/XML (advanced permission matrix management: editors, voters, readers).Architecture Modernization: Industrialized the legacy application by integrating the View Binding pattern and deeply restructuring Adapters to enhance fluidity and make the Java code highly scalable.Technical Environment | KOTLIN, JAVA, JETPACK COMPOSE, VIEW BINDING, XML, JIRA, GIT, POSTGRESQL.Business Environment | Software Editor / Early Childhood & Health
Recommendations
JJ
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Education
- Application Developer - AndroidOpenClassrooms2022Le développeur d’application Android est un expert en développement mobile, spécialisé sur Android. Il est responsable de la création, du développement et de la maintenance d'applications mobiles pour les smartphones et tablettes Android. Le développeur d’application Android travaille sur l'interface utilisateur, les fonctionnalités, et veille à ce que l'application soit performante et sécurisée.
- Information Technology TechniquesCégep Alma2019Développer et concevoir des applications de la programmation jusqu’à l’interface, de leur architecture à leur ergonomie.