Portfolio & Blog

Guillaume Bailleul

Senior Software Engineer
Lille, France | LinkedIn: linkedin.com/in/laibulle | GitHub: github.com/laibulle

Professional Summary

Senior software engineer with 12+ years designing and shipping high-scale systems across HR tech, maritime AI, and IoT. I combine architecture ownership with hands-on execution across backend, frontend, and mobile.

I have deep expertise in Elixir/Phoenix and strong experience with Go, TypeScript, React, and distributed data systems. I focus on business outcomes, maintainability, and pragmatic delivery in cross-functional, international teams.

Core Strengths

Distributed systems and scalable backend architecture
Elixir/Phoenix, Go, TypeScript, React, React Native
Legacy modernization and monolith-to-microservices transitions
API design and integration-heavy platforms
Engineering leadership, mentoring, and technical strategy

Selected Experience

Andjaro | Senior Software Developer | 2021 - Present

Architected and developed core HR platform capabilities in Elixir/Phoenix
Maintained and modernized critical Symfony legacy services
Co-architected mobile workflows with React and Clojurescript integration
Built integrations with payroll, ERP, planning, and SIRH systems

Independent (Pagily) | Freelance Software Engineer | 2019 - 2021

Led architecture and product delivery for a document management platform
Built backend services in .NET/C# and frontend in React
Delivered React Native mobile app and OCR/ML indexing pipeline

Agence Dernier Cri | Senior Software Developer | 2016 - 2019

Architected and implemented Mailjet SendAPI v3.1 in Go at very high scale
Built real-time monitoring systems with Elixir/Phoenix and React Native
Stabilized and modernized critical legacy systems under delivery pressure

Technologies

Elixir, TypeScript, Go, C#, Python, PHP, React, React Native, PostgreSQL, Cassandra, MongoDB, Docker, Kubernetes, AWS, GCP

Languages

French: Native
English: Professional working proficiency