David Guyonvarch
Senior Backend Engineer 🚀 at Zeliq
About
Lead / Tech Lead Backend Developer with 18+ years of experience building and evolving web applications in production environments. I specialize in designing clean, scalable, and maintainable backend systems, with a strong focus on architecture, long-term impact, and team efficiency.
I apply Web-Oriented Architecture principles pragmatically, choosing the right patterns according to business and technical constraints (RESTful APIs, Clean & Hexagonal Architecture, CQRS, DDD). My goal is always the same: reduce complexity, control technical debt, and enable teams to move fast with confidence.
I’m highly comfortable with JavaScript / TypeScript across the stack. On the backend, I mainly work with NestJS, and on the frontend with React (MERN stack).
As a Tech Lead, I take ownership beyond code: defining best practices, mentoring developers, driving architectural decisions, and continuously improving code quality and delivery pipelines.
Work Experience
- Lead efforts to stabilize legacy systems, reduce technical debt, and improve system reliability
- Plan and prioritize a legacy refactor/migration in collaboration with product and stakeholders
- Drive backend architecture and technical roadmap using NestJS/TypeScript
- Mentor developers and enforce best practices to improve code quality and delivery
- Designed and maintained scalable, production-grade backend services using NodeJS/TypeScript
- Implemented event-driven architecture to decouple domains and improve scalability
- Took ownership of production readiness, focusing on observability, monitoring, and alerting
- Used production metrics and incident feedback to drive reliability, performance, and architectural improvements
- Participated in the redesign of a legacy application toward a microservices architecture
- Acted as technical and business referent within the team
- Defined and enforced development guidelines and best practices
- Improved and maintained the CI/CD pipeline, enabling faster and safer deployments
- Mentored developers and supported their technical growth
- Contributed to long-term architectural and platform evolution
- DĂ©veloppement Web Services
- Architecture logicielle
- Evolution et maintenance de la plateforme de build
Volunteer
- Managing and maintaining the festival’s web site
- Providing IT and technical consulting support
- Ensuring reliability and continuity for a high-visibility public event
Education
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2004 2009
Conservatoire National des Arts et MĂ©tiers
Titre RNCP
Concepteur Architecte Informatique
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2002 2004
Lycée Rabelais
Brevet de Technicien Supérieur
Informatique de Gestion