Arbeitsmediziner. Wien

Physician and Independent Entrepreneur

Thomas combines two professional roles: his work as a radiologist at the hospital and his independent practice as an occupational physician. And in between: appointments, company visits, vaccinations, examinations, organization, and the obligation to document everything properly. “My workday is varied. There really is no typical workday, because I’m on-site at different clients. It ranges from a regular office business to parking garage operators.”

In his industry, companies purchase an hourly quota of occupational health services. Time tracking is legally required. “Depending on company size, a certain amount of occupational health care time is mandated by law,” Thomas explains. Every undocumented hour means extra effort and can be financially disadvantageous – “If I don’t log it, I end up paying for it myself.”

Looking for a Mobile Solution

The spreadsheets worked well at first for a handful of companies. But the more companies Thomas managed, the clearer it became: the system doesn’t scale. New rows, different folders, multiple files – the friction was constant. And it’s precisely this friction that causes entries to be made late or forgotten entirely. On top of that, time tracking on the go was a problem: “Using Excel on a phone is pretty terrible.”

Why Kimai On-Premise Was a Game Changer

When Thomas was looking for alternatives, he asked ChatGPT about open-source time tracking. That’s how he found Kimai. Beyond cost efficiency, self-hosting was a decisive factor for him. “I like having my software in my own hands,” Thomas says in the interview, citing specific advantages: control over the system and operations, data sovereignty, and independence were key.

Kimai as a Building Kit for Real Life

Thomas deliberately keeps his Kimai usage lean and only uses what truly makes everyday work easier:

• One project per client per year to cleanly map the hourly quota
• The same activity for all clients, since he provides only one type of medical service
• Time entries in Kimai after completed appointments
• Quarterly invoices to enable flat-rate billing

And because Kimai keeps its source code open for further development and Thomas himself programs, he also built his own extension for quarterly invoices, precisely tailored to his occupational health setup.

Timai – a Smartphone App for Kimai

Things got even more interesting when Thomas realized that while the web interface was sufficient, he preferred having an app in hand during his daily routine. An existing third-party Kimai app didn’t suit his needs, so he quickly decided to build one himself. “It can’t be that hard” – with basic programming knowledge and support from AI tools, he started development.

On a free weekend, Thomas sat down and developed a clear vision of how the app should feel. On Sunday, he turned it into code with AI assistance, so that the first real entries could be processed by that evening. He also added an offline mode so the app could reliably accept entries without an internet connection and sync them later. “Programming is easier than ever today – or at least it’s becoming increasingly easier when you have a basic understanding and prior experience in software development.”

The Timai app can be installed on both Android and iOS devices. “The app is on my first home screen. At the latest when I unlock my phone, it reminds me.”

The Future of Open Source and Vibe Coding

Open source doesn’t mean having to develop everything yourself. Rather, it means being able to adapt systems to your own requirements when needed. And in the age of vibe coding, this customization suddenly becomes realistic: Kimai On-Premise is not a rigid off-the-shelf solution, but an open framework that can be adapted to different use cases.

“You just have to dare and not say – I can’t do it. And not everything has to work right away on the same day. Good things take time.”

Thank you, Dr. Thomas Entner, for the interview and best of luck with your company!