Freelancer profile translated to English.

Description

CTO / Senior full-stack developer (8+ years)

My specialty: taking over and stabilizing early-stage or AI-built products when they start to break under their first real users — security, scalability, technical debt, production deployment. The classic scenario: it works in a demo, it collapses at scale, or it blocks a large enterprise security audit.

What I do concretely:

— Audit & redeployment of existing applications (performance, security, architecture, infra costs)

— Design and development of products from scratch (web & mobile)

— CTO / technical lead role for startups and SMEs in transformation

Some achievements:

— Complete digitalization of an SME, from field intervention to invoicing: ERP Next.js + 2 Flutter apps, and new AI products

— Platform designed and developed from scratch to production

— Support for startups from 0 to fundraising (up to €9M)

Stack: Node.js, Next.js, React, TypeScript, Flutter, MongoDB, AWS — from product to infra.

Method: before any commitment, I offer a short, fixed-price diagnostic. You know exactly what's wrong, the cost of not fixing it, and the price of the correction — risk-free for you.

5.0/5 across all my missions. Response within 1 hour.

Industry field of expertise

Languages

French
Native or bilingual
English
Fluent

Workplace preferences

Remote only

Primarily works remotely

Acquaprotection
CTO
CIVIL ENGINEERING
May 2025 - Today (1 year and 3 months)
Villeneuve-Loubet, France
Acquaprotection had no digitalization of its system. They asked me to digitize everything, from intervention to invoicing. Today I mainly work on improving the deployed ERP and on the company's new AI products. I created 2 Flutter applications + an ERP in Next.js.
Next.js Node.js Flutter Digital Transformation Product Owner
Mate APP
CTO – Mate Circle
SOCIAL NETWORKS
December 2024 - Today (1 year and 8 months)
Barcelone, Spain
As CTO of Mate Circle, I designed and developed the platform from scratch, from the initial idea to production deployment.

I led all technical and product decisions with a clear objective: to build a high-performance, scalable, and fast-to-launch application.

🚀 Achievements
- Development of a cross-platform mobile application with Flutter
- Creation of a web platform with Next.js
- Design of a robust backend API with Node.js
- Implementation of the complete technical architecture (frontend, backend, data)
- Structuring of the product and prioritization of features
Next.js Flutter Node.js CTO React.js
Smatchy
Fullstack Developer
SPORTS
December 2023 - August 2024 (8 months)
Biot, France
I joined a team in rush mode to release the application quickly. The application allows athletes to find sports partners. Built with NestJS for the API and Angular / Ionic for the mobile application, I wasn't a fan of the technologies, but we managed to achieve something good in the end.
Node.js NestJs Angular Angular 12 Ionic 4

Check out Guillaume's experience

Gwenaelle

CONVERGO-MOBILITY

Reviewed on 4/13/2022

Guillaume was able to deliver very clean code within the deadlines that perfectly matched our expectations and the defined architecture. He was proactive in suggesting welcome improvements. We highly recommend his services to those looking for a seasoned developer who knows multiple technologies, business aspects, as well as UX. Guillaume is passionate and will go the extra mile to help you solve your problem.