Team Developers


  • Klaas Joosten, B.  CEO – Founder
    Klaas is now CEO of ZEEF and was the Chief Technical Officer of Mbuyu /M4N, the company that among others employs JDevelopment. Klaas is creator of the vision behind the filter ZEEF. ZEEF filters the world’s information with the help and expertise of passionate experts.
    My ultimate GOAL is to help people find the right information with our product.


  • Arjan Tijms, MSc Lead Developer/Software Architect
    The overall software architecture and the concrete realization of our development process are areas Arjan thinks about. As Lead Developer of the M4N team, Arjan is responsible for a coherent structure of the source code, as well as training and coaching the other developers in his team. Arjan graduated together with Hongqin at the University of Leiden to obtain his MSc (Computer Science, High performance computing). He currently specializes in Java EE techniques, such as EJB (maintains wikipedia article), JSF, JPA, JMS and JTA.

  • Bauke Scholtz, BSc Senior Java Web Developer
    Bauke, also known as “BalusC” in many online communities, comes with a strong background knowledge in Java EE web application development. HTTP, HTML, CSS, JS, JSP, Servlet, JSF, Facelets, he knows pretty much everything in depth. He (re)writes code with high standards of quality. Very specific functional requirements are in no-time turned into elegant code. He is currently mainly working on the front-end of ZEEF web application.

  • Jan Beernink, MSc Senior Java Backend Developer
    Jan is a strongly technical inclined and serious Java developer. After finishing his studies at the Free University of Amsterdam, Jan gained practical experience with Java at a consultancy firm and obtained Java certificates like SCJP and SCDJWS with truly amazing scores. Right after starting at M4N, Jan additionally obtained his SCBCD with an amazing score again. Currently Jan is working at the very heart of the back-bone of the M4N software system. Together with Arjan he periodically spot checks the code base for areas that can be improved (best practices, conventions, etc) and educates other developers how to improve their code.

  • Hongqin Chen, MSc Mid-level Java Developer
    Hongqin holds a Master of Science degree for Computer Science (University of Leiden) and works with us as a Java developer. Hongqin has developed our internal lunch management application (using a combination of JSF and Spring) and is the main developer of an important part of the M4N architecture: the Notification System (a JMS/EJB3 based central hub for collecting and processing notifications originating from other parts of the application and dispatching them to multiple destinations). She has additionally developed parts of M4N’s menu system and the RESTFull API. Hongqin monitors and trains our intern Shan.

  • Dennis Brouwer, B. System integration, hardware tuning, occasional Java developer
    Dennis likes to tune servers and systems to the max by tweaking them over and over again and not letting a system rest before every button has been tried and every wheel has been turned. Give him a server and eventually smoke will come out of it. Apart from this, Dennis monitors overall system performance, keeps a close eye on naming consistency for artifacts in our main DB, sets up our development and beta environments, prepares scripts for hardware or service migrations and, last but not least, participates in the development process with a little Java programming here and there. Is there anything Dennis doesn’t do?

  • Robin Eggenkamp, MSc. Mid-level Objective-C/iPhone developer, Junior Java Developer
    Jack of all trades Robin has studied Software Engineering at the University of Amsterdam and now studies Science Education and Communication. Next to his studies he’s a part-time member of the JDevelopment team. Together with a number of fellow students, Robin has modernized M4N’s e-mail functionality thoroughly using AJAX and JSF together with the RichFaces component library. Robin has the talent of making himself at home with a new technique in the blink of an eye and applying it in a natural way. Besides Java developer, Robin is mainly an iPhone developer. He sells iPhone apps in Apple’s App store, and has won one of only 400 student scholarships to attend the 2009 Apple WWDC in San Francisco. For M4N, Robin has build and maintains our iPhone app.

  • Rick Boerebach Junior Java Developer
    Rick is a young and eager rising star within M4N. He has developed our Android application and also maintains this. He has displayed an aptitude for discovering security vulnerabilities in web applications. Rick has recently improved our “blocking system”, which is a system used to block views, clicks and leads for various reasons.


  • Arjan Pronk Assistant tester
    Arjan pronk is currently studying business oriented computer science at the HVA Amsterdam and strengthens our testing department by helping Anton with the more technical issues associated with testing. Arjan has strong capabilities for scripting tests (Selenium among others) and is well at home with computer technology in general.


  • Tijn Lambrechtsen Senior System Administrator and Monitoring
    Tijn is highly experienced with setting up server monitor systems. He’s currently engaged with making sure that no single emergency condition is missed by the team by setting up a world class monitoring system for all M4N servers.

  • Dineke Tuinhof, MSc General problem solver, Mid-level Java Developer, Business requirements
    Dineke graduated in Artificial Intelligence at the VU University Amsterdam and has worked for many years with us as Java developer. She has recently started to broaden her horizon and migrated to a role of general ‘problem solver’. She’s highly intellectual and investigative. At M4N, Dineke likes to look at the actual meaning of numbers to humans. She rewrote the algorithms of our rating system, and re-engineered the way we track status codes for our statistics. Recently Dineke has focused on perfecting the business rules associated with handling clicks and leads and has implemented those in our ad server. Additionally, Dineke posses strong communication skills, which she uses to explain the finer details of some of our technologies to customers and to discover requirements that people have about our applications.

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