Mathieu Decaffmeyer

End-to-End Software Consultant


I bring over 15 years of experience in developing modern, globally competitive web solutions that deliver an exceptional user experience. My focus is on creating systems with maintainable architecture and code, guaranteeing the enduring success of the products.

Key focus areas:

  • Dedicated to ensuring code quality and developing maintainable software.
  • Simplifying complexity by building systems in manageable, clear parts.
  • Enhancing user experience through easy-to-use, self-explanatory interfaces.

Tech Stack

Highlighted below are my preferred tech stack. Nonetheless, I view programming languages and tools as secondary to the broader goal of finding the best solutions.


My area of greatest proficiency and active community engagement. I contribute to open-source projects in Elixir, appreciating its fault tolerance, high availability, and functional programming features.


Fundamental toolkit for modern web development. Proficient in these core web technologies to craft interactive, visually appealing, and responsive web interfaces.


Attracted to its simplicity and ease of learning, ideal for efficient developer onboarding which contributes to long-term project success. Planning to learn and integrate Golang into my skillset.


My roots in development began with PHP. I value its safe request-scoped architecture and ease of deployment, recognizing its ongoing relevance in modern web development.


Although my experience with Java/C# is primarily from my academic days, I recognize their widespread use in many of today's systems and the substantial job market they offer, making them valuable for broad-scale applications and team-building.

My Philosophy

Code for humans, not machines

My primary goal is to craft clean, understandable code that prioritizes readability that fellow developers can easily understand and work with. Clear and accessible code enhances maintainability, ensuring the project's long-term success.

Complexity is easy, simplicity is hard

Through my experience, I've embraced the 'less is more' philosophy, aiming for simplicity and clarity in the applications I write. Writing a complex codebase is easy; creating simple, clean systems is the real challenge. This approach marks the distinction between seasoned and less experienced developers, and I continually strive to refine this skill.

Mutable state eats puppies

My evolution as a programmer has led me from object-oriented to functional programming. I now favor declarative approaches, immutable structures, pure functions, valuing stateless design over stateful complexities. High-quality code not only guarantees longevity and maintainability of software but also enhances developer experience (DX), playing a crucial role in an application's success.

Focus on the user, not the product

My approach prioritizes understanding and enhancing user experience (UX) as the key to an app's success. Instead of getting lost in product details or making assumptions about user needs, I focus on actively listening to users.

If you thought naming your child was hard, try naming a variable.

—Carla Notarobot

Professional Experience

Full-Stack Developer

Mar 2020 – Feb 2024

Developed a finance tracking tool for NGOs from scratch, covering backend, frontend development, UI/UX design, and deployment.

Software Architect

Jun 2022 – Jun 2023

Evaluated application complexity and new developer onboarding challenges. Recommended improvements and reported on technical debt's business impact to the CTO and founders. Provided coaching on design principles and best practices.

Full-Stack Developer

Jun 2021 – Dec 2021

Developed a real-time application to increase citizen involvement in government projects, enabling discussions, voting, and idea sharing via video conferencing and interactive forms.

Full-Stack Developer

Apr 2017 – Mar 2020

- Developed a React-based stock management app from scratch to efficiently track and manage daily medication packets for resthome clients.
- Building various internal-use web apps to optimize pharmacists' internal workflows and processes.

Full-Stack Developer

Jan 2017 – Apr 2017

Migrating ING's website to a modern, responsive design for improved user experience and accessibility.

Full-Stack Developer

Dec 2015 – Jan 2017

- Refactoring critical legacy, buggy applications for the delivery of daily medication packets to rest home patients, ensuring each packet's content and timing are accurate.
- Building various internal-use web apps to optimize pharmacists' internal workflows and processes.

Full-Stack Developer

Jan 2008 – Dec 2015

- Building presentation websites for clients in various sectors.
- Developing an application for doctors, enabling online appointment bookings and automated email and SMS reminders for patients.

Web Developer

Sep 2006 – Jan 2008

Develop an internal Java web application for booking seats on a private airplane shuttle between Brussels and Luxembourg, featuring seat selection and flight scheduling.

Web Developer

Mar 2006 – Jun 2006

Create an app for remote management of digital displays in businesses, featuring easy upload and scheduling of ads and media and real-time updates.


Business management
Bruxelles Formation

Sep 2009 – Jan 2010

Computer science
Institut Paul Lambin

Oct 2003 – Jun 2006

About me


Mathieu Decaffmeyer


40 y/o


English, French, Dutch

Personal traits

Analytical, Creative, Self-reliant, Can-do attitude, Takes ownership, Supportive, Multicultural, Compassionate

Contact me

Design is not just what it looks like and feels like. Design is how it works.

—Steve Jobs