Curriculum Vitae


Harmen Janssen
Harmen Janssen
Date of birth
11 February 1985
Harderwijk, The Netherlands

Work experience

2021 +
Tech lead at GRRR Creative Digital Agency
2008 - 2021
Senior web developerat GRRR Creative Digital Agency
2007 - 2008
Full-stack developerat Dutch Internet Works
2006 - 2007
Freelance web developer


2003 - 2006
Eindhovense School, Multimedia Design


  • I write high quality PHP code. I focus on maintainability and testability. I'm knowledgable about best practices like the SOLID principles, Gang of Four design patterns and Domain-Driven Design.
  • I have a lot of experience planning small and large web applications and their architecture. I can account for scale, but can also be pragmatic. I have the experience to know when to apply both.
  • I lead a growing team of developers. I coach their personal development and I'm a sparring partner to solve day-to-day technical problems.
  • As tech lead I'm responsible for setting the course of the company's overall technical output. I ensure the team's technical choices are aligned with that strategy.
  • I'm a proficient (technical) writer. I'm able to explain complex technical topics in documentation and blog posts. For a sampling, see my writing on the GRRR Tech blog.
  • I have solid experience with all of the three different front-end technologies; HTML, CSS and JavaScript. I know their distinct domains and the way they interact with one another.
  • Next to object-oriented programming I've studied functional programming in JavaScript and Haskell. I've created a library bringing functional programming paradigms to PHP.
  • I have a general interest in programming languages, and am able to quickly pick up new ones.
  • I have a decent understanding of accessibility, and I'm very motivated to put out accessible front-end code. I consider inclusivity to be an important value.
  • I have a solid understanding of Git. On numerous occasions, I have helped teammates who ran into trouble. I've formulated our general Git workflow, given multiple internal presentations and have written multiple articles on the subject.
  • I have successfully divided applications into microservice-based architectures. This has given me a good understanding of the AWS landscape and I'm experienced in various AWS services, such as Lambda, APIGateway, DynamoDb and others.
  • I've completely refactored a large legacy codebase into a modern Laravel application.

Personal interests

  • I'm the father of a pretty cool boy and girl.
  • I'm an experienced amateur cook. I take cooking very seriously and strive to really understand the techniques. When I'm totally exhausted or stressed, cooking lifts me up.
  • I love doing sports. I'm into weight training, kickboxing, and running. If I wasn't suffering from osteoarthritis of the knee, I would probably be playing basketball a lot.
  • I read quite a lot of books.
  • I like bird watching. Being out in nature and searching for birds calms me down. 🪶