It's not just apps, it's Japps

Freelance Software Development


JAPPS is the commercial name under which I (Jochem Cornelis) offer my software developer skills. I operate from, and preferably in the Amsterdam (Netherlands) area (Haarlem to be more specific), but if the pandemic has learned me anything, it is that (fully) remote work is perfectly feasible.

My main mode of operation is against an hourly rate, but fixed-price can be discussed (as can other business opportunities such as equity ;).

Skillset (hard)

Having been fascinated by software development since I was a kid, and being an eager and fast (self) learner, I bring 30+ years of development experience to the table. This experience covers a wide range of platforms (server, web, desktop, mobile, and a hint of embedded) and techniques. This versatility also facilitates quickly absorbing new knowledge. Instead of trying to enumerate all of this, I’ll focus on what I’ve done lately:

  • Server side Java development (JPA, MySQL, REST, JSON, Protobuf)
  • Mobile development, mostly iOS (Objective-C, Swift, Core Data, BLE)
  • Mendix development (web and mobile, both hybrid and native, building pluggable widgets & React Native modules)
  • JavaScript and React / React Native (including Firebase)
  • I have an affinity and a lot of recent experience in what many call IoT

Skillset (soft)

I can communicate in Dutch and English, verbally and in writing. As software development is about solving problems, I find it worthwhile to bring them all to the surface beforehand and translate them into clear choices between effort and (user) value, indicating sweet spots wherever possible. I can take full responsibility for a project, but am just as comfortable working in or with larger teams, adhering to any processes, tooling, or coding conventions in place.


You can contact me through, or LinkedIn.


JAPPS was originally founded by a co-founder and myself. Originally we aimed at mobile health (mHealth), writing mobile solutions for various organizations (contract-based) while working on our own body of personal health tracking applications and applying for large European grants in cooperation with scientists. We also worked on a few side projects with others and under different names (Mappat, Webvink). When my co-founder left our startup (in good faith), I pivoted towards broader freelancing.