Freelancer profile translated to English.
Back to original languageAbout Sébastien
Full Stack Developer specialized in Java, Spring Boot, React, and PostgreSQL, I help VSEs, SMEs, and project owners create reliable, modern, and business-adapted web applications.
I am involved in the design of complete applications, the development of secure REST APIs with JWT, the creation of responsive React interfaces, database modeling, integration of external services, bug fixing, and improvement of existing projects.
My background combines software development, project management, and a sensitivity to 2D/3D graphics. This versatility allows me to design technically structured, user-friendly solutions that are consistent with my clients' identity.
Notably, I designed AgencyOS, a multi-tenant SaaS agency management platform centralizing clients, projects, tasks, billing, and automations, as well as Ink Red Plumes, a full-stack platform for managing and selling books.
As a former entrepreneur, I take the time to understand your business and needs before developing. My goal: to deliver a clear, maintainable tool that is truly useful to your business — not just code.
French
Native or bilingual
English
Fluent
Can work on-site
Amiens (up to 50km)
Experience
- Agencyos.FrIndependent Full Stack Developer — React · Spring Boot · PostgreSQL · AISOFTWARE PUBLISHINGApril 2026 - May 2026 (1 month)Amiens, FranceDesign and development of AgencyOS, a multi-tenant SaaS platform for agencies, consultants, and freelancers wishing to centralize their business management in a single tool.AgencyOS integrates CRM for clients and contacts, project, phase, and task management, time tracking, quotes, invoicing, payments, expenses, and profitability dashboards and indicators.The platform offers several spaces adapted to different uses:• Manager Interface to manage clients, projects, teams, budgets, and finances• Team Interface to view assigned projects, take on tasks, and log time spent• Client Portal to track project progress and gain visibility without solely relying on email exchangesTime tracking allows comparison of planned budget, actual workload, production costs, and revenue to quickly identify deviations and project profitability.The application also includes an interactive demo with sample data, a progressive onboarding process, and an embedded help assistant presenting features directly within the interface.End-to-end architecture designed with React, TypeScript, Spring Boot, PostgreSQL, and Docker. The multi-tenant core ensures data isolation between organizations, with management of roles, permissions, and secure JWT authentication.Business automations via n8n, AI features via Claude API, HTTPS deployment on VPS, CI/CD with GitHub Actions, and Uptime Kuma monitoring.Project completed from A to Z: needs analysis, EMD, data dictionary, architecture, front-end/back-end development, security, testing, deployment, and maintenance.Application and demo: agencyos.frSource code: private GitHub repository.
- BeatStudioFull Stack Developer React / TypeScript – Creator of BeatStudioSOFTWARE PUBLISHINGMarch 2026 - March 2026Amiens, FranceBeatStudio – Web Music Sequencer (Web Audio API)Design and development of BeatStudio, a web application for music creation inspired by DAWs (Digital Audio Workstations) like FL Studio.The application allows composing, editing, saving, and exporting musical sequences directly from a web browser, without installation or server.Features developed:• Multi-track music sequencer with interactive grid• Management of melodic instruments, percussions, and sound effects• 4-octave virtual piano with step-based note assignment• Import of custom audio samples (.wav, .mp3, .ogg)• Real-time audio effects (reverb, delay, distortion, filter)• WAV export and project saving in JSON format• BPM and loop management, and per-track mixing• Automatic local saving and library of preset patterns• Responsive interface inspired by professional DAWsTechnical Stack:React 18 • TypeScript • Vite • Tone.js • Web Audio API • CSS Modules • GitHub Pages • GitHub ActionsProject completed end-to-end: architecture design, audio engine development, complex state management, advanced user interface, and automated deployment.Demo:spiritzen.github.io/BeatStudio/Source code:github.com/Spiritzen/BeatStudio
- MotionStudioFull Stack Developer React / TypeScript – Creator of MotionStudioSOFTWARE PUBLISHINGFebruary 2026 - February 2026Amiens, FranceDesign and development of MotionStudio, a professional web animation editor inspired by Premiere Pro and After Effects, entirely executed in the browser without a server or installation.Complete development of the application with React, TypeScript, and Fabric.js to enable the creation, animation, and export of visual content directly from the web.Features developed:• Canvas-based graphics editor with object, image, video, and text management• Professional timeline with multiple tracks, clips, cutting, and keyframes• Advanced animation with GSAP and custom easing curves• Audio management via Web Audio API with real-time synchronization• WebM/MP4 video export directly from the browser• CSS Keyframes export and automatic GSAP code generation• Undo/Redo history and project saving system• Formats adapted for social networks (YouTube, TikTok, Instagram, LinkedIn)Advanced front-end architecture based on React 18, TypeScript, Fabric.js, GSAP, Zustand, and Web Audio API. Automated deployment via GitHub Actions and GitHub Pages.Project completed from A to Z: functional design, software architecture, development, performance optimization, deployment, and maintenance.Online application:spiritzen.github.io/MotionStudio/Source code:github.com/Spiritzen/MotionStudio
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Education
- Professional Title: Application Designer DeveloperAFCI Amiens2025Formation certifiante RNCP niveau 6 (Bac+3/4) orientée conception et développement d'applications professionnelles. Compétences acquises : • Analyse des besoins et rédaction de cahiers des charges • Modélisation de bases de données (MCD, MLD, SQL) • Développement backend Java, Spring Boot et API REST sécurisées • Développement frontend React, JavaScript et interfaces responsives • Gestion de projet Agile / Scrum • Sécurité applicative (JWT, Spring Security, OWASP) • Docker, Git, GitHub et déploiement d'applications • Tests, maintenance et amélioration continue Réalisation de plusieurs projets full-stack, dont Ink Red Plumes (plateforme e-commerce de livres), Trajet Formateurs (gestion des missions et déplacements) et AgencyOS (SaaS de gestion d'activité multi-tenant).
- Management School CertificateProméo AFPI 80022017Certification Éco-Responsable d'Équipe – Niveau 6 (Bac+3 / Bac+4) Formation certifiante orientée management opérationnel, animation d'équipe et amélioration continue dans un environnement industriel et organisationnel. Compétences développées : • Management et accompagnement des équipes • Communication professionnelle et conduite de réunions • Résolution de problèmes et prise de décision collective • Utilisation d'outils d'amélioration continue et de performance • Animation de groupes de travail et séances de brainstorming • Gestion des priorités et organisation de l'activité • Conduite du changement et mobilisation des collaborateurs • Développement d'une démarche éco-responsable dans l'organisation Maîtrise d'outils et méthodes de management appliqués à des situations réelles d'entreprise : analyse de problèmes, recherche de solutions, animation d'ateliers collaboratifs, amélioration des processus et pilotage de plans d'actions. Travaux pratiques réalisés autour de problématiques concrètes d'entreprise, de projets d'amélioration continue et de méthodologies collaboratives favorisant la performance collective. Certification obtenue auprès de l'UIMM / AFPI 8002 le 23 juin 2017.
Certifications
- Certified RNCP Level 6 Title (Bac+3/4) focused on professional application design and development.AFCI AMIENS2025
- Management School RNCP Level 6 (BAC+3/4)Proméo AFPI 8002 Center2017