Hi there, we are Calendar42!

Solving problems that are unsolvable

Meet our top notch team!

Michel Boerrigter

Founder / CEO

Lelian Net 


Erwin Dassen 

Technical Lead

Angela Colgan

HR Advisor

Jesse Harting

Project Manager

Eelco Kodde

Delivery Manager

David Lijnse

Product Manager

Maarten Lodewijk

UX designer

Siva Pachaiyappan

Lead Test Engineer

Ambar Das

Test Engineer

Edmon Marine

Full Stack Developer

dr. Gürsel Karaçor 

Data Scientist

Lars v. Gemerden

Algorithm Engineer

Shiplu Mokaddim

Backend Developer

Shea Meyers

Backend Developer

Gerard Petersen

DevOps Engineer

Stefan de Konink


Wesley de Konink

DevOps Engineer

Anatoliy Kaminskyi

Backend Developer

Mahdieh Saeed

Backend Developer

Maud van den Broek

Backend Developer

Jacob Turner

Algorithm Engineer

Sifferina de Jong

UX Designer

Athanasios Angelakis

Lead Data Scientist 

Aggelos Balatsoukas

GIS Data Analyst

Xinyuan Liu

Technical Support Engineer

Eric Vierboom

Financial Controller


Check our vacancies!

Our background story

We have our academic roots at the renowned Delft University of Technology, to us it is evident to surround ourselves with true specialists and shape a culture where it is natural to find solutions for complex issues beyond the status quo. Together we share the fundamental believe that if you don’t understand the structure of a difficult problem, then you can’t solve the problem, ever.

Also, we...

  • spend time to dive deep into ancient studies, academic papers or natural sciences to find answers for the mobility problems we face today and in the future.
  • spread our knowledge given the fact that we are an energetic multi-cultural bunch of people with backgrounds ranging from former rocket scientists, data engineers, developers, designers and mobility specialists. 
  • sit down to have lunch together on a daily base and share a beer at least once a week. This might sound small, but we all value the time to catch up and share stories.

  • love to break the rules, and are passionate about designing and building outstanding solutions that enrich people's lives.


Concepting & Design




Communication & GIFs


Sprint Planning & Knowledge base


Code Repo's


Language of choice


App Containerization


Our dev environment


Continuous Integration


Infrastructure automation


Web Framework of choice


Database of choice


Web Server


Our REST standard


Message broker of choice


What is your recruitment procedure?

We typically take the following steps:

  1. We screen all applications and might request some additional information, for example some examples of your best work or anything that provides additional context to your CV.
  2. If you pass our initial screening we will invite you for a first meeting in which you will sit down with our hiring manager for the job at hand. This meeting will ~1 hour and can be done over Skype.
  3. In most cases we would like to see how you manage and handle typical problems. Therefore we will create a "homework" assignment, that shouldn't take more than 1-2 hours to finish.
  4. After passing the previous steps we will schedule a contract meeting to discuss the terms and to wrap up the stipulations, if successful this is followed with a team lunch to get to know the rest of the team & vice versa.

Are there any perquisites included?

  1. We normally start with a one year contract including a one month trial period.
  2. All our contracts come with a standard travel expenses coverage, an annual personal development fee and an optional laptop agreement based on the "necessity criteria", market-based wages & loads of fun. 

What is your on-boarding procedure?
We welcome you on your first day & make sure your work place is set up. After this you will partner with one of us and we make sure that the first days are spend on getting you up to speed to become part of the team. 

Next to this we schedule a trial period meeting, and assuming you will pass the trial period, semi annual personal development and annual evaluation meetings.

Can you give me an idea of your standard method of working?
This of course depends on your job, but every (customer) journey needs a great story. A story we can divide into chapters, that become more and more exciting after every page in the book. How we manage this?

  1. We start our sprint cycles with a kick-off event;
  2. We keep each other posted with a daily stand up meeting; and
  3. We finish our sprints with a delivery and well earned drinks.

To help us control our future developments and ensuring our continuous evolvement, we have epic sessions in which we share our adventures.

How have you arranged the rules of the game of working as a team?
We have setup a social contract, they are a result of how we believe teamwork thrives best and basically boils down to:

  • Think first. Come with solutions, not with problems.
  • Do what you tell people you will do.
  • Keep track of yourself.
  • We can handle a lot of bad news, but we hate surprises.

On top of this, we as a team act based on these guidelines:

  • Trust > control: no politics, no fear
  • Community > structure: we don’t tell you in detail what & how, but feel free to ask for help
  • Agile > scrum: rules are good, break when needed
  • Quality > time: changing the world doesn’t happen overnight

Enough about us, what about you?