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Marten den Heijer


Software Engineer

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About Me

I am a dedicated software engineer with a strong focus on delivering high-quality, sustainable, and future-proof software solutions. My extensive knowledge of programming languages, frameworks, libraries, and code principles enables me to excel in providing exceptional software solutions. I possess a comprehensive understanding of the entire software development process, from translating business requirements into technical specifications to successful implementation.

Collaboration and effective communication are among my greatest strengths. I thrive in team environments, working collaboratively to achieve shared goals. Serving as a lead developer at Qfact, I am adept at guiding a team of software developers.



Work Experience

2022 - Present

Lead Software Engineer | Qfact

As a lead developer at Qfact, I am responsible for leading a team of software developers. My tasks include guiding the development process, making architectural decisions, and ensuring code quality. Additionally, I am involved in designing and implementing complex software solutions for our clients.

  • Managing internal and external stakeholders.
  • Training junior Software Developers.
  • Taking leadership for ongoing projects within an agile development process.
  • Developing technical solutions, discussing and presenting them to the team.
  • Contributing to strategic-level discussions for Qfact's software product roadmap.
  • Making Architectural Decisions.


4 years

Software Engineer | Qfact

As a software engineer at Qfact, I worked on various projects within software applications. I was responsible for developing and maintaining software solutions and collaborating with a team of developers to complete the projects.

  • Design and implement software solutions.
  • Work together with a team of software engineers to implement software solutions.
  • Design high quality and sustainable software solutions to maintain SaaS-applications.
  • Adhere to SOLID principles.
  • Adhere to Clean Code principles.
  • Working in an agile environment (SCRUM).

Skills & Expertise

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Leadership and Management: Demonstrated effective leadership skills, overseeing the efficient operation of a software development team and ensuring project goals were met.


Agile Methodologies: Proficient in utilizing agile methodologies, including Scrum, to streamline development processes and enhance overall project efficiency.

Technical Expertise: Adept at developing and implementing innovative technical solutions, utilizing a wide range of technologies, including:

  • Python
  • Java, Spring Boot Framework
  • C#, .NET, Unity Engine
  • Javascript, NodeJS, VueJS, React, Angular
  • Python, Natural Language Toolkit (NLTK), Gensim, spaCy, Tensorflow, NumPy, Pandas, PyTorch
  • PHP, Laravel, Phalcon
  • MySQL, Cassandra, MongoDB, Elasticsearch, Redis, Firebase, PostgreSQL
  • Cloud hosting (Google Cloud Hosting, DigitalOcean, Azure, AWS)
  • Serverless (AWS)
  • Git, Github, Gitlab, Jenkins
  • Electron, Ionic
  • ChatGPT API, Llama-2

My Projects

July 2023 -

October 2023


  • Python
  • SpaCy
  • ChatGPT
  • Llama-2

December 2022 -

May 2023


  • Python
  • Elasticsearch
  • Microservices

July 2022 - March 2023

Person Analyzing Reports in an Office


  • NodeJS
  • VueJS
  • MySQL
  • MongoDB

November 2021 - December 2021


  • NodeJS
  • VueJS

August 2021 - December 2021


  • NodeJS
  • Cassandra
  • RabbitMQ
  • MongoDB

May 2021 - August 2021


  • .NET
  • MySQL
  • VueJS
  • Mobile App Development

March 2021 - April 2021

Data Codes through Eyeglasses


  • NodeJS
  • VueJS
  • Eventstore
  • MySQL

july 2017 - december 2021


  • C#
  • Unity Engine
  • Photon Engine
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QIntelligence - Phase 2: Document Information Analysis

I led the development of a transformative Proof-of-Concept at Qfact, enabling automated content analysis and precise project suggestions from user-uploaded documents. This involved intensive research into Natural Language Processing (NLP) and Python libraries like SpaCy, NLTK, and Gensim. Leveraging cutting-edge technology such as ChatGPT and Llama-2, I successfully built a Proof-of-Concept for a system that significantly reduced administrative workload while delivering highly accurate project recommendations, showcasing my expertise in NLP and innovative problem-solving.

QIntelligence - Phase 1: Document Indexing

I led a project for Qfact aimed at indexing documents, marking the first step in a strategic initiative to harness user document information within existing software platforms. The project's goal was to establish an adaptable infrastructure capable of accommodating all document-related requirements. My responsibilities encompassed researching methods for storing and utilizing document information, designing the architecture and infrastructure, and overseeing implementation. The infrastructure's strength lay in its future-proof design, achieved through extensive stakeholder interviews and careful consideration of potential solutions. The project involved creating a Python service within the existing microservices architecture, utilizing an Elasticsearch database for document storage, and introducing user requirements for document uploading, indexing, and full-text search.

Analysis Functionality Enhancement

As the leader of the Qfact Analysis Functionality project, I oversaw the complete project lifecycle, from initial functional design to successful release. This project was initiated due to the declining performance of existing analysis methods as data volumes increased. Collaborating with the software architect and senior developer, I played a pivotal role in designing the overall architecture and granular software modules. We implemented the project within a new service in our microservices architecture, using a MySQL database for frequent data synchronization. The innovative approach involved configuring analysis reports through a user-friendly interface, dynamically creating complex MySQL queries via cronjobs, and maintaining specially created MySQL reports tables. This design ensured rapid report loading while dealing with complex data spread across multiple microservices.

Online Game Engine

I developed a dynamic online game engine using object-oriented programming in Javascript. This comprehensive engine boasts a frontend client framework which can be integrated in an HTML canvas, alongside a high-performance NodeJS backend that seamlessly facilitates networking functionalities using Socket technology. Leveraging this framework, I successfully created two games, showcasing my proficiency in creating software solutions on an abstract level.

Game Engine Client Framework Repository (Gitlab)

Game Engine Backend Repository (Gitlab)

Integration #1 (Gitlab)

Integration #2 (Gitlab)

Eventstore Development

Working closely with the software architect, I contributed to the development of a new Eventstore for a cutting-edge Qfact software platform. The Eventstore served as a pivotal database for storing business logic in the Qfact platform, leveraging the Event Sourcing pattern for data storage. The choice of an Eventstore was driven by the need for enhanced accountability and auditing capabilities. SCRUM methodology guided our software development process. My responsibilities included designing the software, implementing the code, and facilitating migration and integration into the existing software platform. The Eventstore was built using JavaScript, with Cassandra for event storage and MongoDB for tracking read models.

Car Sharing Mobile Application

In this project, I developed a Mobile Car Sharing Application designed to manage shared vehicles efficiently. The application facilitated the tracking of car usage, notifying users about activity via push notifications and emails, and calculating mileage and fueling costs to ensure equitable cost-sharing among users. The application boasted a user-friendly design for intuitive interactions and used a straightforward architecture tailored to meet the project's requirements. The front-end was developed using VueJS, compiled into a mobile app, while the back-end was implemented in .NET, with data persistence handled by a MySQL database.

Collaborative Board Application

During this project, I created a Collaborative Board Application that enabled users to collaborate seamlessly on a shared digital board. This platform allowed real-time synchronization of cards, text, videos, and images among all users, providing a clutter-free space for teams to share and document information effectively. To achieve this, I leveraged Socket technologies to synchronize changes across all users, ensuring a smooth collaborative experience. Additionally, I implemented a well-structured and modular Vue front-end, allowing for easy extensions and modifications. Notably, this Vue structure facilitated multiple users editing the same card concurrently without causing any unexpected issues. Furthermore, the NodeJS backend utilized eventstore technologies to optimize performance, minimize database queries, and reduce memory usage on both the client and server sides. Frontend Code (Gitlab),

Game Development in Unity

I developed a variaty of engaging games using the Unity Engine and C#, driven by my passion for game development and a desire to explore new languages and technologies. Through these personal projects, I acquired valuable experience in object-oriented programming and honed my skills in C# within the Unity framework. Additionally, I delved into online game development, gaining a comprehensive understanding of networking technologies and principles that continue to be relevant in my current work.



My main


Is quality

Engineer or Architect

Work additude

  • Skilled at creating complicated software solutions.
  • Understands what stakeholders need.
  • Connects software development with business goals.
  • Works well in teams.
  • Manages conflicting stakeholder requirements effectively.
  • Solves problems with attention to detail.
  • Knows how to use agile software methods well.
  • Always learning new things.
  • Cares about making sure software is good quality.
  • Communicates well with people who aren't technical.
  • Encourages new ideas and ways of doing things.
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Marten den Heijer

Software Engineer

I’m open for new connections, check out my Linked-In:

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