Luc D.

Pennylane est une plateforme financière française combinant logiciel de comptabilité et outils de gestion. Elle connecte experts-comptables et entreprises via un système partagé, centralisant facturation, dépenses et données en temps réel. L’architecture repose sur un monolithe orienté API et traitements asynchrones (background jobs).

J’ai rejoint Pennylane en tant que Senior Backend Engineer dans la squad IAM (autorisations et permissions), initialement comme seul senior d’une équipe nouvellement créée, au sein d’un monolithe de plus de 300 développeurs. L’environnement était très structuré : CI avancé, Git hooks stricts, CODEOWNERS et organisation claire (Junior à Staff, EM, PM).

Ma mission principale a été de concevoir et piloter un nouveau système de permissions basé sur CanCanCan, remplaçant une solution legacy difficile à maintenir. J’ai défini l’architecture, développé les fonctionnalités clés et assuré l’intégration dans le monolithe, avec des contraintes fortes de migration et de cohérence des données. J’ai collaboré avec plusieurs équipes pour garantir une adoption fluide et une base scalable.

J’ai également contribué à des sujets transverses (Sidekiq) et utilisé des outils avancés comme Datadog, Sentry et des solutions d’IA (Claude, Dust) intégrées au workflow.

Cette expérience m’a confronté aux enjeux du passage à l’échelle d’un monolithe : Packwerk pour gérer l’ownership du code, merge queues, coordination inter-équipes et fortes contraintes de qualité. J’y ai renforcé mon expertise Ruby/Rails et ma capacité à mener des projets complexes.

Through the global network Proxify, I’m currently working with Faktus — a fast-scaling company that uses cutting-edge technologies to act as a financial intermediary between various entities in the real estate market.

I work with the latest versions of Ruby, Rails, and Sidekiq, as well as Turbo and Stimulus, in a fast-paced environment. The team is still human-sized, which gives me the opportunity to contribute across the board. My focus is on building new features while actively managing and reducing technical debt. We are also relying on Active Admin.

A key part of the business involves integration with a third-party Banking-as-a-Service provider — an area in which I’ve now built strong expertise.

The environment is dynamic and stimulating. I’m enjoying working with modern Rails tools like Turbo and Stimulus, and I strive to bring both professionalism and my startup experience to help the team grow efficiently.

During my collaboration with Welligence, I worked as a Data Engineer on a tool built for internal data scientists. It was used to scrape and inject data into multiple PostgreSQL databases, as well as generate various reports in PDF and Excel formats.

The role had a strong coordination aspect. Welligence is a U.S.-based company with developers across Europe and Vietnam, and each global economic region had a head of data relying on the tool and working on a different time-zone. This required effective communication skills and experience with Ruby on Rails, Jenkins, Sidekiq, and some Python.

As the company scaled, we faced several reliability and performance challenges. One of my key contributions was building a GeoJSON import feature to visualize oil field shapes on a 3D globe.

While the experience was valuable, the role became increasingly support-oriented, with limited opportunities for hands-on development. I decided to move on in search of a position with a stronger focus on software engineering.