Ukraine is seeing a new type of ecosystem being built, where creators can quickly test their ideas and products in battlefield conditions. Few stories exemplify this more than Caslog, a piece of medical kit developed by Fabio Hamilos-Keller, an officer in the Swiss Armed Forces, and Mykyta Puz, an officer in Ukraine’s 12th Special Forces “Azov” brigade.
“I just asked a lot of questions”
How the two met is a story in and of itself. Hamilos-Keller – a software developer who commands a medical unit in the Swiss military – had traveled to Warsaw in December 2025 to participate in the European Defense Tech hackathon.
The hackathons serve as a way to bring European creators into contact with Ukrainian realities. Puz, who before joining Azov had been a manager in AI companies, was there to act as a mentor.
Hamilos-Keller was impressed by Puz: “I just listened to Mykyta and asked him a lot of questions. At some point, we got to the topic of combat care and then how soldiers are evacuated. We nailed the problem down together. There I developed the initial idea of Caslog, pitched it, and won the hackathon.”
How Caslog works
The idea behind Caslog is simple. It’s a small device that fits onto the arm or leg of a wounded soldier. It can be switched on to record audio, filter data, and create a patient record, which is stored both on the device and in the cloud. As the wounded soldier is moved from place to place, whoever takes over their care can immediately know what they’re dealing with.
The process of moving an injured soldier can be multiple steps over hours or even days – from the battlefield where he was injured, to a field position, all the way to the rear – and records are hard to keep. According to the team, Caslog fills this gap: the device can be tapped with the user’s phone, and the Caslog app immediately displays all available information.
“Very few ideas make you go, ‘That’s it’”
When Puz heard the idea, he loved it: as chance would have it, he had been put in charge of Azov’s digital services development and had recently learned about issues surrounding casualty records.
Puz recalls the event: “It was not my first hackathon as a mentor, so I knew the drill. You have people with a lot of energy, with a lot of focus on technology, but with a distant realization of what part of that technology is actually needed right now. My role is to give this reality check. You’re happy to help, but very few of the ideas make you go, ‘That’s it.’”
Hamilos-Keller was different, though, says Puz: “at the Warsaw hackathon, I heard a lot of crazy ideas from different teams, and then I saw this shy guy, who was talking combat medicine.” The two spoke for a while, but Puz wasn’t really impressed until the next day, when he saw that Hamilos-Keller had incorporated much of his feedback into his presentation for the hackathon jury.
When asked about any reservations he may have had about working with somebody from Western Europe, Puz is emphatic: “Fabio might have been from Zaporizhzhia with the very same results, with the same attitude. It’s just that such an attitude is still rare in Europe. I’m seeing that it’s changing, albeit very slowly.”
“I feel kind of ashamed that we haven’t thought of this already”
In the chaos of the hackathon wrapping up, Puz didn’t get Hamilos-Keller’s number. However, a month later, Hamilos-Keller reached out to him while on a trip to Kyiv, and the two got together to further develop the idea; Caslog was born.
Puz took the idea over to the deputy commanding medical officer of the Azov brigade, who said the best possible thing they could: “I feel kind of ashamed that we haven’t thought of this already,” a quote now prominently displayed on the Caslog site.
However, it didn’t stay at that, and Puz made good use of his connections within the Ukrainian military to run more field tests – the true force behind Ukrainian innovation, as we previously discussed in this interview with Himera’s founder.
“This has to work”
Puz summarizes the findings: “We recently ran a validation with seven other units that confirmed the very same problem, which is patient records on the pre-hospital stage are extremely fragmented or often completely lost, to the point that you get a casualty at the door of a stabilization point, and you can do the visual assessment, and that’s basically all you know.”
There seems to be a clear market fit, but Hamilos-Keller remains pensive: “It’s always nice to get something validated, to have someone tell you that it’s a great idea, but I’m still not satisfied. This has to work. It has to deliver an added value to the effort of defending Ukraine and the rest of Europe.”
Getting funded
While Hamilos-Keller tinkers further on Caslog, Puz has set out to get funding for their product “We definitely need money to make this product real,” he says. “We decided early on that we want to create the first version of the product by ourselves, bootstrapping it.”
The hope is that having a first version of the product will give Caslog some added leverage when dealing with VCs and other investors. However, the duo is running into some realities that have more to do with boardrooms than battlefields.
“VCs are searching for something that can give them at least, like 100 times the returns on exit or whatever,” says Puz, then continues: “I don’t think this model is really sustainable for defense because while a lot of money is being thrown at it, not all of it is actually practical and the real problems aren’t being noticed.”
“I am trying not to die here”
Puz says Caslog’s goals are different: “VCs invest in a bright future in 50 years when everybody’s a billionaire. I don’t care. I don’t wanna be a billionaire. I have a problem to solve, because the war is here right now. Maybe five years from now, you’re gonna have a unicorn exit, well, good for you. I am trying not to die here, with an enemy trying to kill me on a mostly daily basis.”
Instead, the two say, they would like to get an investor who will help them make a product and stay in the game over the long term. “If we solve it correctly in a proper, pretty close timeframe, this solution will make money,” says Puz.
Hamilos-Keller takes a similar view, but includes what’s happening beyond the current battlefield: “I’m convinced Switzerland faces the same fundamental threat as Ukraine. It’s just a different time for us now. We’re maybe years back in time, and Ukraine is ahead in a sense. But the geopolitical change affects Switzerland as much as any other country in Europe.”
Hamilos-Keller thinks for a moment, then continues: “my country’s not at all prepared to face anything even close to what Ukraine is facing right now. Our military is in a very bad state. Anything that might help to modernize it, and this includes Caslog, will help.”
