Tegonal Open Source Week 2025

In early April, Tegonal held its annual «Open Source Week». For that week, regular work is put on hold as far as possible and the whole team takes time to work on open-source projects. The idea is to explore new subject areas, try out interesting frameworks and technologies, start projects, or improve existing tools and libraries. All of this happens in the context of open source and open data, so we give something back to the open-source community while deepening our own knowledge. Last but not least, the team experience matters too: we work intensely on something together in different line-ups, and have fun doing it.

This year, we built or kicked off four projects in very different areas:

• Age verification with the federal e-ID: Since the end of March, the e-ID has been in public beta. As a «proof of concept», we built a small device with a simple app that could be used in a bar, for example, to check a person's age with the e-ID, sharing only the information that's actually needed for that purpose.
• Analysing how the yield of PV systems develops over time: We built a simple prototype app that lets owners of solar installations record their PV system's output over a longer period and compare it with the expected yield. This shows whether a system becomes less productive over time, e.g. because the solar panels get dirty or age.
• React Router templates: These templates give you a solid basis for starting an application that uses React Router to navigate between views. There are different templates for different use cases (server-side or client-side rendering), which you can then easily extend and adapt.
• Java API and compiler plugin for Atrium: Atrium is a modern, expressive assertion library for Kotlin, designed to make testing software easier. We worked on a Java API that would make Atrium comfortable to use in Java projects too. We also tinkered with a Kotlin compiler plugin for Atrium.

We'll cover each of these projects in more detail in separate posts.