William Barillon

Development of reusable production-ready service architectures for backend and data systems. • Designed reusable backend service architectures focused on maintainability and production readiness • Built API and service design patterns for Python-based backend systems • Worked on PostgreSQL-based systems with emphasis on administration, testing, and hardening • Designed resilient and idempotent data pipeline patterns for production workflows • Built Docker-based development and deployment environments for reproducible setups • Defined deployment and configuration workflows for service-based architectures

Technical writing focused on software engineering topics, based on real development experience. • Published 30+ technical articles covering containerized Python backend development, best practices, and infrastructure topics • Topics include Docker-based environments (e.g. cron jobs), testing fundamentals for junior developers, and software architecture concepts • Articles rank among top search results (positions 1–5) for relevant technical queries • Generating 1,000+ monthly reads across published content

Due to a serious medical condition, I had to resign from my role at ArianeGroup. Following a surgery in early 2025 and a recovery period, I gradually resumed professional activity, including technical writing and open-source development. I later continued working on personal engineering projects and open-source contributions.

Worked on flight software tooling for Ariane 6 at ArianeGroup, contributing to mission-critical Python-based development in a safety-critical aerospace environment. • Developed Python-based scripts for mission data generation used in Ariane 6 flight software workflows • Contributed to the design and improvement of testing strategies for internal engineering tools, including degraded and failure-case test scenarios • Documented delivered features to ensure traceability and long-term maintainability of engineering tools • Worked in a safety-critical context where correctness, traceability, and reproducibility were strict engineering constraints

Worked on a large-scale Python system within a consulting environment involving distributed systems, streaming pipelines, and a multi-component codebase. • Contributed to the development and maintenance of a large Python backend codebase in a distributed system context • Worked in an environment with multiple teams and evolving requirements, requiring strong coordination and adaptability • Improved understanding of production constraints including codebase consistency, technical debt, and long-term maintainability • Applied debugging and refactoring practices in a context with limited or inconsistent automated testing coverage • Strengthened awareness of software quality practices, particularly around testability and system reliability in enterprise environments

• Designed and led an internal SQL training session for consultants (live remote session), covering query structure, maintainability, CTE usage, and debugging best practices. Prepared all training materials including slides and case studies. The session was recorded and reused internally as training content • Obtained Databricks Spark Developer Associate certification • Obtained Google Cloud Professional Data Engineer certification • Worked on a technical demonstrator exploring integration of reactive Vue.js components into Django templates without Node.js or build tooling, enabling lightweight server-rendered interactivity

Joined a fintech startup, where I worked on building end-to-end features from backend architecture to operational UX in a compliance-grade context for the compliance department. • Developed Django backend services within Docker-based development environments to ensure reproducible execution and consistent setups across environments • Built and maintained ~60 data pipelines executed twice daily via Airflow for automated processing and operational workflows • Developed compliance-critical features for financial operations and reporting, including fraud suspicion reporting workflows and user financial activity dashboards • Built an in-application reporting feature allowing users to generate PDF and Excel reports for compliance and operational tracking • Internal communication system with secure messaging and file handling • Security improvements across application layers (data handling and access control) • Built on Django 3 with integrated Python pipelines and targeted JavaScript enhancements for UI responsiveness

Built end-to-end Python/Django applications for operational needs in a small association context, from requirements gathering to production deployment. • Designed and developed a Django application for culture monitoring and data collection (mobile-first usage in field conditions) • Designed a multi-step form to replace a long single-page input, improving usability for non-technical users • Designed database models and application architecture from scratch • Implemented responsive UI and backend logic for real-world usage constraints • Participated in requirements gathering with end users and iterative UX validation • Deployed and maintained the application in production environment

Responsible for website maintenance, improvements, and digital performance optimization in a small organization context. • Redesigned and maintained website structure and content to improve usability and clarity • Implemented SEO optimizations that improved search rankings, achieving top 1–3 positions on most target queries • Debugged and resolved technical issues across website components (front-end) • Improved back-office usability for non-technical users through workflow simplification • Implemented basic security practices and operational safeguards • Collaborated with owners to translate business needs into technical improvements