Freelancer profile translated to English.
Back to original languageAbout Guillaume
Are you looking for a React / Node.js Tech Lead?
You are in the right place.
I am a software engineer with 10 years of experience.
My specialties: Typescript, React, Node.
I have collaborated with companies like Louve Invest, BNP, and Crédit Agricole...
I am able to:
- Design, develop, and maintain features in line with business needs
- Participate in the drafting of detailed technical specifications
- Analyze the impact of product design on the IT technical architecture
- Develop the front-end in Typescript React
- Develop the back-end in Node.JS, NestJS, Express, Scala Play, or Java SpringBoot
- Set up databases (SQL, PostgreSQL, MongoDb, RealTime Db)
- Set up CI/CD
- Write technical documentation
- Perform unit and integration tests to ensure code quality
- Participate in refactoring, continuous improvement, and code review contributions
For leadership:
- Define the technical vision and ensure long-term architectural consistency
- Coach and mentor the technical team to foster collective skill development
- Make decisions on complex technological choices and resolve critical blocking points
- Establish high quality standards (Clean Code, TDD, Design Patterns) and ensure their application
- Ensure the technical interface between business stakeholders and the development team
I also have knowledge of: ElasticSearch, Kafka, Prisma, TypeOrm, Metabase, GCP, Redis, GraphQL.
Do you have a project?
Contact me, I respond in less than 1 hour.
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French
Native or bilingual
English
Fluent
Can work on-site
Paris (up to 50km), Lille (up to 50km), Bordeaux (up to 50km), Lyon (up to 50km)
Experience
- KlineoFull Stack Engineer React Node.js PythonMEDICALSeptember 2025 - March 2026 (6 months)Paris, FranceKlineo is a health tech startup aiming to help cancer patients find clinical trials.The company has 13 employees and is used by 70% of French oncologists to help tens of thousands of patients find their clinical trial.I joined the development team to assist in the realization of Klineo's flagship product.My team consisted of: 4 developers, 1 product owner, 1 CTOImpact: I contributed to preparing a funding round and thoroughly restructured the codebase to improve application quality and reduce bugs.My responsibilities:- Design, develop, and maintain features in line with business needs- Participate in the drafting of detailed technical specifications- Internationalization of the platform for launch in 5 new countries.- Cross-functional migration of a data model across 4 services (TypeScript + Python/AI) without service interruption.- Develop the front-end in Typescript React- Develop the back-end in Node.JSTechnical context: TypeScript, React, NestJS, PostgreSQL, GitLab CI, GraphQl, Python, Prisma, git, Redis
- LouveInvestSenior React Node.js DeveloperBANKING AND INSURANCENovember 2021 - July 2025 (3 years and 8 months)Paris, FranceLouve Invest is a fintech company that aims to invest in real estate investment funds.The company has over 40,000 clients.I joined the two founders as the company's first developer. When I left, there was a team of 4 developers.My responsibilities:- 0 to 1 Execution: Complete architecture of the transactional system that enabled the transition from €100k to €400M in cumulative flows.- Operational Efficiency: Massive automation of processes that reduced the need for human resources by a factor of 10 (5 employees vs. 50 estimated without automation) to handle the same volume of business.- Management & Culture: Recruitment of the first 4 technical employees and definition of the team's operational standards.- Innovation: Integration of AI (LLM/Parsing) into the product for monitoring and OCR.- Develop the front-end in React- Develop the back-end in Node.JS- Coach and mentor the technical team to foster collective skill development- Establish high quality standards (Clean Code, TDD, Design Patterns) and ensure their applicationTechnical context: Typescript, React, Node.JS, GCP, Express.js, ElasticSearch, Firebase, git, Github, PostgreSQL, playwright, NoSQL
- ReachFiveFull Stack Scala / React DeveloperFebruary 2019 - June 2021 (2 years and 4 months)Paris, FranceReachFive is a SaaS in the IT security sector that aims to manage customer identities and access (CIAM - direct competitor to Auth0).The company manages over 330 million user accounts for over 100 clients with a 99.99% SLA.The technical team consisted of two squads of 4 developers, a project manager, and a CTO.My responsibilities:- Taking over and refactoring a complex existing Scala codebase- Migrating a front-end to React + Typescript- Managing application scalability through: multi-threading management + file import stream usage + application distribution- Agile SCRUM project management- Continuous delivery CI/CD- Performing unit and integration tests to ensure code qualityTechnical context: Scala, Elastic Search, React, Play Framework, PostgresSQL, Firebase, Typescript
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Education
- MIAGE LicenseUniversity of Bordeaux2013La MIAGE est une filière universitaire alliant informatique de pointe et management, dispensée au sein d’un réseau national de plus de 20 universités. Référence de la double compétence depuis 1970, elle forme des profils hybrides capables de traduire les besoins business en solutions techniques complexes. La filière a déjà diplômé plusieurs dizaines de milliers d'experts. J’y ai consolidé mon savoir-faire en architecture des systèmes d’information.
Certifications
- 42422016