Jonathan Gelin

Passionate in Optimizing Software Development Cycles

May 8, 1985
🇬🇧 English (Fluent)
🇫🇷 French (Native speaker)

Summary

Whether it's as a Software Engineer, Tech Lead, or Architect, if it involves software development, I'm in!

My journey began 19 years ago in Java development before transitioning fully into the dynamic world of JavaScript/TypeScript and its powerful ecosystem. Now, I unify diverse technologies to enable seamless full-stack development, ensuring systems work efficiently and scale effortlessly.

I support companies through their software development cycle challenges by utilizing Nx monorepos, micro frontends, robust testing strategies, and a touch of Extreme Programming philosophy.

Every day for me is like waiting for the next episode of my favorite series—filled with learning, sharing, and growing together. Indeed, I'm as passionate about coaching and sharing knowledge as I am about coding.

I am the father of two incredible boys, and I am endlessly grateful to my wife for supporting my passion every day.

Experiences

Caseware logo

Nx Consultant & Full Stack Development Architecture

Caseware

Mar 2024 - Present · 10 mos

Remote

Collaborated with the Dev Success Team to maintain and improve a large Central Monorepo (~900 projects) alongside multiple Distributed Monorepos. As an Nx expert, implemented an architecture designed to maximize the benefits of the Nx ecosystem.

  • Upgraded Nx from v16 to v19.8
  • Refactored custom utilities from legacy Project Configuration to Nx's Project Graph
  • Unified and simplified the Monorepo architecture by leveraging Nx Plugins
  • Unified workflows across multiple tech stacks (JavaScript/TypeScript, Java, Python, Go, .NET)
  • Streamlined CI/CD GitHub workflows
  • Paired and coached development teams for better Monorepo integration
  • Implemented a new CI-managed release process
  • Contributed to task organization for the Dev Success Team
TypeScriptMonorepo ArchitectureMicro-Frontends ArchitectureNxAngularNestJsGitHubWebpackJestESLintCypressDevOpsNodeJsYarnPnpmOpenAPIWebstormGitHub ActionsGitHub CopilotJavaPythonGo.NET
Entain logo

Architect Team Lead

Entain

Jun 2023 - Dec 2023 · 6 mos

Remote

Oversaw the migration of multiple repositories and projects into an Nx monorepo for Entain. Developed the migration strategy, conducted coaching and pairing sessions with developers, configured the CI/CD pipeline, and ensured effective use of tools to uphold best development practices.

  • Architected the monorepo with a focus on Angular and .Net
  • Developed a migration kit with monorepo conventions to streamline integration of external repositories
  • Deployed various Nx plugins to create custom executors and generators
  • Established a new process to build multiple themes and integrate them seamlessly into various applications
  • Implemented a new CI-managed release process
  • Executed a full CI/CD implementation on GitLab, incorporating Distributed Task Execution and Distributed Caching
  • Enforced best development practices to ensure long-term quality and maintainability
  • Led weekly meetings for project updates and progress tracking
  • Organized and generated tasks for the architecture team
Nx.NETCI/CDGitLabDistributed Task ExecutionDistributed CachingMonorepo StrategyDevelopment CoachingAngularTypeScript
Selligent Marketing Cloud logo

Software Architect & Tech Lead & Mentoring

Selligent Marketing Cloud

Apr 2020 - Jun 2023 · 3 yrs 2 mos

Hasselt, Flanders Region, Belgium · Remote

Established the new frontend architecture across multiple teams, including coaching/pairing with developers, configuring CI/CD pipelines, and ensuring adherence to best development practices. Migrated a large AngularJS application to a micro-frontend architecture.

  • Designed the monorepo architecture to group applications, libraries, shared components, and e2e tests
  • Implemented a micro-frontend architecture using single-spa and Angular
  • Configured e2e testing processes and tooling using Cypress
  • Delivered a full CI/CD implementation with Azure DevOps, supporting incremental development
  • Established best development practices to ensure long-term quality and maintainability
  • Coached developers on JavaScript functional programming, CI/CD, XP (pair programming, code reviews, training), BDD, and TDD
  • Coached clients on adopting an agile mindset and continuous development practices
NodeJSTypeScriptRxJSAngularTailwindStorybookWebpackMonorepoMicro-FrontendSingle-spaModule FederationSystemJSESLintSonarQubeOpenAPINrwl NxSASSAngular MaterialJestCypressYarnWebStormAzure DevOpsDockerJiraGitAzure App InsightsAzure Storage
Thalys logo

Software Architect & Tech Lead & Agile Coach

Thalys

Nov 2018 - Apr 2020 · 1 yr 5 mos

Brussels Region, Belgium · Hybrid

Configured and led a full-stack software development team, following the Spotify squad model. Supported the team by implementing core architectural components and coaching them on eXtreme Programming (XP) principles. Acted as a bridge between customers and users, guiding them through Agile principles and fostering a continuous development workflow.

  • Architected a monorepo grouping backend services, frontends, and shared libraries
  • Designed a frontend architecture with reusable components across multiple applications
  • Collaborated with the team to define key UI/UX ergonomics
  • Developed a backend architecture based on microservices
  • Implemented a caching system using Redis to enhance overall performance
  • Delivered a full CI/CD pipeline using Docker in a Kubernetes environment
  • Established best development practices to ensure long-term quality and maintainability
  • Coached developers on JavaScript functional programming, CI/CD, and XP practices
  • Configured authentication and authorization using Azure AD and centralized roles
  • Designed the business domain model in collaboration with customers
  • Configured the Kanban board with the team to optimize task management
  • Set up metrics and reporting to improve team velocity and enhance user satisfaction
  • Coached customers on Agile methodologies and continuous development
  • Mentored other internal development teams on various architectural topics
TypeScriptNode.jsTailwind CSSAngularAzure DevOpsMonorepo (Nrwl/Nx)RxJSGraphQLNestJSPostman APIYarnCypressJestMicrosoft AzureAgile MethodologiesKanbanGitLabDockerKubernetesSassRedis

Recommendations

Karel Frederix's picture

Karel Frederix

Senior Software Engineer at Marigold

I've had the privilege of collaborating with Jonathan for over two years at our organization, and I am thoroughly impressed by what he was able to achieve as a freelance Frontend Architect. Jonathan was entrusted with the challenge of leading our teams through the migration of a substantial legacy frontend codebase to a modern, state-of-the-art monorepo, employing a micro-frontend architecture utilizing Angular and Nx. This transition was monumental.

By the time of his departure, he had not only revolutionized our frontend development landscape but also equipped us with a solid foundation and the essential knowledge to keep innovating further. It felt to me like he moved a mountain, and it's incredible how much I learned from him.

I highly recommend Jonathan to any organization seeking a visionary in modern frontend solutions.

Maarten Cardinaels's picture

Maarten Cardinaels

Tech lead at AvioBook

Working with Jonathan for some years now. He has proven to be a skilled architect, always aiming for solid, clean and maintainable solutions.

At the same time he's a great mentor and coach, taking the time (over and over again) to explain complex topics in an understandable way, while challenging people allowing them to improve.

Learned a lot from him both from a technical point of view as well as good developer mindset.

Definitely recommending him for a broad range of projects!

Ben Beckers's picture

Ben Beckers

Software Engineer bij Selligent Marketing Cloud

Jonathan was the architect when we migrated from AngularJS to Angular.

He brought a lot (and I mean a lot) of knowledge to the company.

For me personally, he was able to break down difficult things into small bits so we/I could understand them.
Even for domain specific things, he would come up with solid solutions.
I have never learned this much from anyone, I'm not shy to say he made me a better frontend developer.

Amazing asset to the company and a genuine nice person who cares a lot about his job!

Igor Kalders's picture

Igor Kalders

Engineering Manager at Marigold

Jonathan is an extremely skilled front-end architect with the right mix of knowledge, patience and network to weigh in with authority. Apart from that, he sports a can-do mentality and manages to raise the quality bar across an Engineering department. Sound boarding with him does not get boring: never condescending, always enlightening.

He is one of those rare talents not everyone is lucky enough to work with in their lifetime. If you do, prepare to learn a lot.

© 2025 made with Astro by Jonathan Gelin