Freelancer profile translated to English.
Back to original languageAbout Sébastien
Are you looking for a React.js, Node.js, TypeScript full-stack developer?
Do you need a custom web or mobile application?
You've come to the right place.
Seven years of experience designing, delivering, and maintaining full-stack applications in TypeScript, React, and Node for SMEs, mid-sized companies, and large corporations.
Previous missions
- OMNES Education (EdTech): MatchUp, an internship job platform for students. AI integration, 80% reduction in data entry time.
- Ramify (FinTech, Series A): full-stack development.
- Chanel (luxury): full-stack development.
- ANCT (public sector): Territorial Suite, a digital platform for local authorities. First developer, 30 beta testers in 6 months on the secure messaging service.
- Groupe Rapido (automotive): Week and Go marketplace, 3 million annual visits.
- Tortuga Outdoor (e-commerce): technical co-founder, web and mobile application. 600 users in 3 months.
Stack
TypeScript, React.js, Next.js, React Native, Node.js, NestJS, Express.js, PostgreSQL, MongoDB, Supabase, AWS, Serverless Framework, Docker, GitHub Actions, GitLab CI.
Certifications
- Continuous Delivery and The Anatomy of a Deployment Pipeline (Dave Farley, Better Software Faster)
- Back to the Essence of Agility - Adaptive Agile Project Management (Frédéric Leguédois, Moovence)
How it works
You define your priorities. Fixed monthly budget, weekly production releases. You test and approve each feature before going live. Automated tests at all levels (TDD, BDD, ATDD), automated CI/CD pipeline, zero regression guarantee.
No invoice issued in the first month if you decide not to continue. Monthly renewal, cancellation at the end of any month.
Fixed-price missions. Response within 24 hours on the platform.
Shall we discuss it?
French
Native or bilingual
English
Native or bilingual
Spanish
Conversational
Dutch
Basic
Portuguese
Basic
Remote only
Primarily works remotely
Experience
- DevedanosReact.js Node.js TypeScript Next.js DeveloperEDUCATION AND E-LEARNINGJanuary 2025 - Today (1 year and 5 months)Puteaux, FranceI had the opportunity to work with several clients in 2025:- OMNES Education, an EdTech investment fund owning higher education campuses and developing MatchUp, a job platform for students seeking apprenticeships.- Ramify, a French FinTech startup in Series A that raised 11 million euros in 2021.- Chanel, the French luxury house.I collaborated within multidisciplinary teams composed of developers, business analysts, testers, product owners, project managers, UI/UX designers, lead developers, and experts in SEO, accessibility, and web performance.I performed the following tasks:- Back-end Development: Creation of secure REST APIs with Node.js, Express.js, and TypeScript to manage user data and business processes- Application Security: Implementation of JWT and Microsoft Authentication, with data validation via Zod- Data Architecture: Design of NoSQL models with Mongoose for MongoDB and Azure Cosmos DB- User Role Management: Development of a secure impersonation system- Technical Standardization: Setup of Docker development environments to harmonize tool versions and streamline team collaboration- Front-end Development: Creation of responsive and multilingual user interfaces with React.js, Next.js- Application Modernization: Migration of a React.js application to a new design system based on Figma mockups- Performance Optimization: Improvement of loading times and application fluidity using React hooks, and conducting core web vital performance tests (INP, LCP…)- Complex Data Integration: Creation of an automated pipeline to enrich authentication and profile data- AI Innovation: Development of a CV automatic analysis feature via the ChatGPT API, reducing manual data entry time by 80%
- Tortuga OutdoorReact.js Node.js TypeScript Next.js React Native DeveloperSPORTSOctober 2024 - Today (1 year and 8 months)Toulouse, FranceTortuga Outdoor was founded in 2024 by Corentin Teulet, a full-stack developer from the Toulouse region.Passionate about mountain sports, he noticed that there was no dedicated space for outdoor and mountain sports enthusiasts to connect and share their passion.He therefore created Tortuga with the mission to foster human connections, make the mountains accessible, inspire and be inspired, and share his passion for the mountains and enrich it.I joined Tortuga as technical co-founder alongside Corentin.I performed the following tasks:- Design of the roadmap of features to be developed and their prioritization using a Kanban board, based on Agile and Lean principles and the No Estimates practice- Technological and architectural choices, mentoring and training of developers, including interns- Frontend development of web and mobile applications with Next.js, Tailwind CSS, HeroUI/NextUI, React Native, Expo, Native Wind, TypeScript, Jotai, and Tanstack Query- Backend development of applications, particularly with secure React Server Functions and REST API and RPC endpoints, communicating with the database in Next.js, Supabase, React, TypeScript, Node.js, JWT, Supabase, and PostgreSQL- Development of real-time features with Supabase and the publish/subscribe WebSocket protocol- Implementation of continuous delivery in our work practices (DevOps, Trunk Based Development, CI/CD, Observability) to ensure product stability and scalability while optimizing our resources.During this experience, Tortuga's figures evolved as follows:- Over 600 users in 3 monthsLink to the Tortuga website:
- Suite territorialeReact.js Node.js TypeScript Next.js DeveloperPUBLIC SECTORJanuary 2024 - September 2024 (8 months)Paris, FranceANCT is a French public organization. This agency supports local authorities in their territorial challenges. It has 3,000 employees. It is recognized throughout Europe as a model of administrative innovation. The agency is affiliated with beta.gouv.fr (a program dedicated to the incubation of public digital services).ANCT is developing La Suite Territoriale, a digital platform. It is designed in partnership with ANSSI and DiNum as part of France 2030 Plan. It aims to strengthen the cybersecurity of local authorities. This is a major step forward in local digital sovereignty.The Suite offers three essential and secure tools for local authorities:- protected domain names- a professional messaging service- an online storage spaceThese services are open source, interoperable, and benefit from French hosting.My team consisted of:- 1 project manager- 1 UI/UX designer and Product Owner- 2 Python/Django developers- 2 React.js/Node.js/Next.js/TypeScript developers- 2 deployment officersAs a React.js / Next.js, Node.js, TypeScript developer, my responsibilities were:- Developing a tRPC API in TypeScript, Node.js, Koa.js- Creating interactive components and pages in TSX with React.js, Next.js, and TypeScript- Setting up unit and end-to-end tests with Jest, Vitest, and Playwright- Writing technical documentation on Storybook and Outline in markdown- Configuring the internationalization of the application in English and French with react-i18nextI contributed to the following developments:- The development of an administration console ready to receive its beta testers within 6 months- Access to new fundingHere is the link to the project website:
Reviews
Recommendations
JF
TC
+2
These freelancer profiles also match your criteria
Agatha Frydrych
Backend Java Software Engineer
4.7
(3)
2
Baptiste Duhen
Fullstack developer
4.6
(4)
5
Amed Hamou
Senior Lead Developer
4
(2)
7
Audrey Champion
Web developer
4.3
(3)
4
Education
- Professional Bachelor's Degree in Application Design and DevelopmentMyDigitalSchool Paris2020Bac +3 Javascript, Node.js, React, Testing, Java EE, REST API, MongoDB, J'ai pu remporter avec mon équipe un hackathon de 3j où nous avons développé une appli web faite sur Express.js; développer un projet validant ma fin d'année, aussi fait en Express.js, Handlebars, Node.js, Socket.io, JWT. Cette année en cours m'a donné goût à l'auto-apprentissage, voyant que je progressais mieux en faisant mes propres projets et recherches. J'achetais aussi mes propres cours.
- DOMOTICS BTS (Higher National Diploma)IFA Delorozoy (Montigny-le-Bretonneux, 78)2014Algorithmie, aéraulique, adressage IP, protocoles TCP/IP, KNX, électrotechnique
Certifications
- The Anatomy of a Deployment PipelineCD Training DevOps Courses from David Farley2024