Victor Kropp

UTF-8 Explained

Sat, 14 Feb 2026 18:39:00 +0200

Awesome video explaining how UTF-8 works. Beautifully narrated and easy to understand.

It doesn’t dive deep into emojis but focuses more on text encoding. Some facts, for example, about Hangul encoding were new to me.

Pesonal Apps

Tue, 10 Feb 2026 17:16:13 +0200

Despite being silent about AI on this blog, I’ve been using it for a while now. And not, it doesn’t write posts here instead of me. But I do use it in programming.

Many software engineers worry that AI is going to replace them. To some extent it might be true, we’ve seen impressive results in the past few years. Many models are now capable of generating basic applications, landing pages, or simple games. But there will be a lot of demand for more complex applications, for critical thinking, and architectural decisions.

However, if we take a look at it from a different perspective, AI also opens up a whole new world of possibilities for everyone. Here’s an example.

Pinentry

I’ve been using a Yubikey for my GPG keys for a long time now. But I never really liked the GnuPG’s pinentry-mac password dialog used to unlock my key. It is outdated.

Original pinentry-mac from GnuPG

It became even more apparent on macOS Tahoe with Liquid Glass. But even before that, I couldn’t stand it and quickly hacked my own alternative. I spent a few hours in total to make it work.

My handcrafted alternative from a few years ago

And then some more hours to update it to work with the latest macOS. It worked great and I was happy with it.

Vibe Coding

But today, I decided to task an AI agent to reimplement it. I started with the following prompt on an empty directory:

Create a macOS native popup that will implement Assuan protocol (at least partially) and act as replacement for pinentry program. It should follow Liquid Glass guidelines and present a simple and clean UI.

And it came up with this while I was brewing a cup of tea. Wow, just wow!

What I got in a few prompts from AI

Well, it didn’t work perfectly from the very first try, but I needed to follow up just twice with a few minor tweaks. Overall, it took me about two minutes of active involvement (and 20 minutes in the background) to get it working.

And AI also implemented the given task in many ways much better than I did. For example, it has better organized I/O and tweaked the UI using properties I’ve never seen before.

What’s next?

We are no longer limited by the current tools. It is now absolutely possible to tailor an application to anyone’s needs. It takes just a few minutes and a handful of AI tokens.

I don’t think the profession of software engineer will ever be obsolete. Instead, AI will enable us to create applications that we wouldn’t be able to make otherwise.

Yes, I spent just a day hacking my own solution for a simple task. But I have many more similar ideas, which I wasn’t able to implement yet because of time constraints and priorities. And now I can!

And I’m not alone. Some are replacing paid services spending the same 20 minutes. Others creating an app that they always needed. These are just two I stumbled upon last week. And I’m sure there are and will be many more.

Site update

Sun, 01 Feb 2026 19:29:20 +0100

It’s been a while since I last posted a changelog for this website. So it’s time to recap what have changed since then.

Browsers to remove XSLT support

Two years ago I added a simple XSL transformation to prettify RSS feed as it is shown when opened by a direct link. The support for this (massively outdated) technology is going to be removed soon. Funny, that this specific use case is mentioned in the deprecation announcement. Looks like, I’ll need to add a polyfill to fix that later.

CSS polishing

I keep polishing CSS without changing the looks. I’ve cleaned up the narrow view shown on mobile. But the biggest update is the addition of dark theme.

Initially implemented with JavaScript and manually changing classes, now it uses modern light-dark() CSS function and color-scheme property. Checkout this awesome guide on how to properly use it.

Lists

It appears, I like making lists. Not To-Do lists, although them too, but lists of albums I listen, or series I watch. Or my up-to-date wishlist and bucketlist. All that in addition to long existing lists of books I read and videogames I played.

At the end of 2025 I downloaded my data from Instagram and Twitter and vibe coded two static pages with all content I once posted there.

Load speed

I stumbled upon an article “Why your website should be under 14kB in size” some time ago and decided to implement the advice, at least on my homepage. So I removed all unused and auxiliary stuff, and now it hopefully loads a fraction of a second faster.

Was it necessary? Probably not.

Was it fun to chase it down to 14kb? Hell yeah.

And since I already use a static site generator, why not take another small step to improve load times?

Transitions

More and more browsers are supporting navigation transitions now, and I’ve enabled them too. With all optimization efforts, pages now switch seamlessly, and I enjoy navigating on my site.

That’s it

That’s all I could remember I’ve updated here recently. Again, I’m CEO, Product Manager, Head of Design, and Lead Software Engineer for my homepage, so I can do whatever I want here. And I enjoy it!

Startup Camp

Fri, 30 Jan 2026 10:28:59 +0200

Last week I took part in an internal Startup Camp. The goal was to take an idea for a spin for a week, and prove if it is worth further investment or not.

I didn’t have my own idea, so I joined an existing project. We proudly called as co-founders, even in fact we were just learning basics.

Lessons learned

Idea is nothing without execution

I’ve heard it multiple times, but until you start doing something you might be blinded by the absolute awesomeness of your idea. It is only when you start digging deeper you discover all its hidden sides, and may ultimately come to a conclusion that nobody needs it.

It is necessary to believe in the idea, but it is sometimes as well important to let it go when everyone tells you it is not needed, and research confirms it.

You can talk to random people on LinkedIn

During our research, we contacted 50+ people on LinkedIn each. And some of they answered! We did numerous interview just in few days, talking to former employees of competitor companies and potential and current users of similar software. This helped us a lot to understand our problem understanding wasn’t aligned with the reality.

We dropped the idea, but the spirit lives on

We had an opportunity to continue working on the project if we could have proved it can be successful. Nevertheless, it was also an important experience to close the project before we invested too much into something that can’t be profitable.

One out of fifty

They say that only 1 out of 50 startups survives and is profitable. Well, I need to try just 49 more times.

This is ten percent luck
Twenty percent skill
Fifteen percent concentrated power of will
Five percent pleasure
Fifty percent pain
And a hundred percent reason to remember the name

Remember the name by Fort Minor

Just do it!

Deprecation

Tue, 27 Jan 2026 17:12:11 +0200

After I created my Twitter archive, I started reviewing all my blog posts. The goal was to replace Twitter embeds with pre-rendered tweets from the archive. There were two reasons for that.

First, it ensured the content will remain there even years after publication. For example, my April Fools blog post from 2017 has lost most of its referenced content, because it was deleted sometime in the past years.

Second, Hugo shortcode I used for that is deprecated, and it is required to rename it. I didn’t want to do that. Embedding tweets directly allowed me to work around this and also improve building speed albeit insignificantly.

As a side effect of this activity, I also added some deprecation notes to old content which is irrelevant as of today. I’ve irregularly writing here for around ten years, so there’s been some.

Book review: The Big Five for Life

Fri, 16 Jan 2026 16:59:00 +0200

Just finished ~~reading~~ listening “The Big Five for Life” by John Strelecky (narrated by the author) and it is one of the most inspiring books I’ve ever read.

Set as a fictional story¹ about a successful entrepreneur, it describes his way of leading his multiple companies. But in fact, it goes much further, and focuses on universal life advices that would benefit everyone, not only company owners and leaders.

Here are some easy to remember, but very impactful concepts from the book.

Museum Day

Imagine that at the end of your life, a museum is built that displays every single day you lived. Every action, conversation, and mood is presented there. If you spent 20% of your life at a job you didn’t like, 20% of the museum will be dedicated to it. And you’ll be guiding others thorough your personal exhibition for eternity.

A Good Museum Day is a day you would be proud to be displayed there.

Purpose for Existing

Everyone has their PFE (Purpose for Existing) – the main goal of their life. Yours should align with the company you’re working on. The book focuses on hiring, but this advice may be applied when you’re applying for a work too.

The concept is also useful in private life just as well. If your and your partner’s PFE differ significantly, it may be impossible for you to coexist in balance.

Big Five for Life

What are the five things you want to do, see, or experience before you die? These are your Big Five for Life.

You should always remember them and ask yourself every day, what have you done to be a step closer to them?

After reading this book, I understood that I don’t exactly what is my PFE, and what items from my bucketlist I would call my Big Five for Life. So, my resolution for 2026 is to figure this out.

★★★★★ highly recommend

Similar to “The Five Dysfunctions of a Team” by Patrick Lencioni. And both have five in their titles. A coincidence? ↩︎

My Twitter Archive

Tue, 06 Jan 2026 17:44:10 +0200

Few weeks ago I downloaded my complete Instagram profile and published an archive here, on my personal website.

Next logical step was to do the same with Twitter, which was once my favorite social network. I left it right after it was overtaken by a billionaire and renamed, but it hosts around 15 years of memories. I don’t want to lose them, so I downloaded archive of my profile and (vibe-)coded a static page from it.

With very little effort from my side I was able to get a 5Mb HTML file and somewhat 400Mb media. With some additional effort from AI and imagemagick/ffmpeg I shrinked them down to 2Mb and 120Mb respectively, which I find acceptable.

I enjoyed glancing through the history and remembering some long forgotten interactions with beautiful people around the world. I’ll miss them, but I’m out of social networks.

Homelab

Sat, 03 Jan 2026 17:13:27 +0200

⚠️

Just a few days after I published this post, my CM3588 broke down and no longer boots. I no longer recommend it to anyone and I’ll publish a postmortem later.

Some 1½ year ago I started my homelab.

I wanted to have a small local server to serve as NAS and a server for private services. I pay for iCloud and Google Drive for photos and documents storage, but I also want to have my backups locally and independently. Also, my wife’s and mine’s Time Machine backups are already quite big and the bill for cloud services would be significant.

The same for local services, which I want to run without dependency on network availability and without sharing too much private information. These are for example, Paperless to store all sorts of documents, or CarConnectivity to track various stats of my car.

Hardware

I chose CM3588 NAS Kit to run my homelab for many reasons:

It is not restricted to some proprietary vendor OS, I run Debian there with any software I want
It runs on ARM, with passive cooling (no noise at all) and low energy consumption
It supports up to 4 NVME SSD drives
I could 3D print a case for it!

My CM3588 based homelab in a 3D printed case

Four SSD drives might be an overkill, but I really wanted it to be fanless and quiet. Increased disk access speed is not that important to me. As for total storage volume, I don’t need much, so a few 2TB drives in RAID array are enough for me.

SSD

For price-performance ratio I initially chose Western Digital Blue SN580 SSDs. However, I wouldn’t recommend them, as two of them crashed suddenly and, of course, at very inconvenient time. Sandisk (which are owners of Western Digital now) replaced them without questions, respect to them. But still, I needed to set up a lot of the things again.

An important lesson learned was that my backups worked and I didn’t lose any unrecoverable data.

Software

As mentioned above, I run Paperless on it, and I will write a separate blog post about it later.

I also want to expand the number of self-hosted services this year with:

Immich for photos
Pi-hole for ad blocking
Syncthing for easy file sync

Do you know any other services worth trying?

2025 in Review

Wed, 31 Dec 2025 12:56:59 +0100

Another year is over, and it is time to follow the annual tradition.

I finished my previous review with a brief mention of year compass. Although I haven’t opened it at all since then, it still influenced my life. Some important things I wrote there were: spend more time with the family ✅, travel more ✅, say ‘no’ to new projects more often ❌.

All in all, I had a lot of great moments this year, and this is how I remember 2025.

Personal

In general, I’d rate this year as good on a personal level. I’ve made some improvements here and there, but nothing to brag about. My smart home and homelab projects are doing great, and I still have plans to share more about them on this blog.

There were sad moments too. Our car has passed away at a solid age of fifteen years. Rest in peace, Ronnie. We will always love you.

Work

My team worked tirelessly on two major releases this year: announcing Compose Multiplatform as stable on iOS, and beta on Web. The trip to KotlinConf was again one of the highlights of the year.

With a workshop, talks with colleagues, partners, and users, and the official conference app rebuilt from the ground up, I was so busy before and during the conference, that I needed some time afterwards to realize how much we have achieved.

I had much fewer business trips in 2025 compared to the previous year, however it still felt too much. I value in-person collaboration a lot, but often all business questions are better resolved asynchronously, and the time together is better spent just hanging out. And we had enough of it this year.

Electric car

VW ID.7 Tourer. Image: Volkswagen

One of the biggest changes for my family this year was a new car and not just any new car, but an electric one. I enjoy driving it whenever I can and am absolutely excited about the future of electric mobility. I learned a lot about EVs this year, and can assure everyone that the infrastructure for them is already there, at least in Western Europe. If you’re still weighing when would be a good time to get an EV, don’t wait, the time is now.

It took me a while to choose one. A major factor for me was to support a European, and even better a German, manufacturer. Unsurprisingly, I decided for Volkswagen, who are together with their other brands are dominating European EV market.

Just a side note: I still commute to the office by bike mostly. And I cycled 1300 km almost exclusively between home and office this year.

Travel

And while I traveled less for business, we made quite a few vacation travels. Not at last because of the new spacious and very comfortable car.

We’ve been to Italy (for the fourth straight year) and this time I bought a transponder for toll roads. What a great idea it was, it saved us at least few hours of traffic jams before the toll plazas during just this one trip. Totally worth its money!

Together with my son we visited Budapest for the Hungarian Grand Prix and witnessed Lando Norris’ win on his way to F1 World Championship triumph.

And finally, we’ve traveled locally this time a lot, including a round trip through almost all Germany’s federal states.

This year I finally realized that I no longer want any social media. Instead, every time I had a spare minute, I improved some detail on my homepage, my very own place in the World Wide Web. I keep saying it every year, but I’d like to write more about it, and post more to my blog as well.

I had some failures too. I started the year with “One emoji a day” and did well for a few months, but then somehow forgot about it and only remembered when it was too late. I’m going to repeat the challenge in 2026.

Fitness and sport

With all the stuff happening in both personal and work life I completely missed all sport events. Wings for Life World Run was sold out faster than I expected, so I missed it despite having a great time there in 2024. I did not ride my road bike even once, and hiked less than I wanted too. The obvious plan for next year is to fix this.

Still, I got not one, but two perfect months on my Apple Watch, and completed all monthly challenges. (And 23 out of last 24, I failed the previous December one because I got terribly sick and had not enough time to catch up)

And this year I reduced my alcohol consumption to almost zero. I can’t yet say I quit drinking completely, but I do it so rare and don’t miss it at all.

I wasn’t as successful in avoiding sweets, I’ll take another attempt starting tomorrow.

Entertainment

Games

I didn’t have much time to play video games this year. In fact, I played only four games in total: completed a Platinum trophy in LEGO Horizon Adventures and Spiderman 2, and finished Death Stranding 2: On the Beach, with platinum trophy there still in progress.

DEATH STRANDING 2: On the Beach

But my personal favorite was the co-op game Split Fiction from the authors of It Takes Two. Together with my wife, we enjoyed their previous game, and their new creation did not disappoint.

Overall gaming gave me what I wanted: a way to relax in the evening without much thinking.

Movies

In the past years I went to the cinema only once a year, and 2025 continued the streak. I haven’t had big hopes for the F1 movie, but it was better than I thought. Fast cars and some Easter eggs for long time fans is a good recipe for a summer blockbuster.

Overall, there are less and less exciting movies I’d like to see, let alone go to a cinema for it.

Series

Last year we watched Silo and Severance and enjoyed their second seasons early this year. We also finally binge-watched 4 seasons of the Stranger Things and are ready for the epic finale.

I appreciate authors going for a risk of producing of a new original story. So, I also have high hopes for the new series from Vince Gilligan (of Breaking Bad and Better Call Saul fame) – Pluribus.

But, yeah, it’s all mainstream.

Books

Absolutely unexpectedly I started listening to audiobooks a lot. Three books last year were just the beginning. This year I listened to nine full-size books, mostly during my commute.

My favorite book of the year was, for sure, the Project Hail Mary by Andy Weir. I finally get to read (yes, I read it, not listened) it after YouTube suggested me to watch a trailer for the upcoming movie. I marked the trailer to watch later, and swallowed the book in under a week, which is a great result, given I didn’t have time for anything this year. It was the same feeling as with The Martian by the same author, who masterfully blends sci-fi and entertaining story.

LEGO

We’ve got annual passes to the LEGOLAND Deutschland (just 1 hour by car from Munich) and visited it multiple times with kids this summer. It could have been my dream as kid, and I’m happy I can share it with my children.

McLaren MCL38 Image: LEGO

2025 sets joined my LEGO McLaren collection just in time for the second consecutive Constructors’ World Championship.

And I started a small personal project of building my apartment in minifigure scale, but it is not finished yet.

2026

The past year was great, eventful, exciting, and satisfying. It was so intense that my energy level towards the end of December was permanently at zero.

My wish for the next year for now is to keep all things as exciting and great as before, but tune down intensity a bit. We’ve planned fewer family trips (but they will be no less scenic), I expect fewer releases of a smaller scale, but even more stability and quality at work.

Overall, I’m looking confidently into the next 365 days and can’t wait to write the next review looking back at how great I spent these days.

52 interesting things I learned in 2025

Tue, 23 Dec 2025 09:49:08 +0200

Following last year’s tradition, here is a list of things I learned this year, one for each week.

Temperature inversion is a phenomenon in which a layer of warmer air overlies cooler air.
In the 1980s, a man with severe OCD shot himself in the head in an attempt to commit suicide. Instead of killing him, the bullet destroyed the part of his brain responsible for his OCD.
In 2003, there were between 50 and 100 people in the US who still had nuclear-powered pacemakers.
SQLite is in public domain, and open source, but is not open for contributions.
A title drop is when a character in a movie says the title of the movie they’re in.
Trains in Switzerland must not have exactly 256 axles, or the signaling system gets confused.
Blue Monday is the name given to a day in January (typically the third Monday of the month) to be the most depressing day of the year.
git was able to track itself from day one.
In 2023, bands occupied just 4% of the music charts–compare to 41% in 1995.
A score bug is a digital on-screen graphic which is displayed at either the top or lower third bottom of the television screen during a broadcast of a sporting event in order to display the current score and other statistics.
The uninhabited Pheasant island in the river Bidassoa that separates France and Spain switches countries every six months.
In ancient Greek religion and mythology, the Moirai—often known in English as the Fates—were the personifications of destiny.
There is a hidden feature to mark file as template in macOS.
European Council maintains a catalogue of ID, passport, driving license, and other legal specimens of many countries.
The Chinese room argument holds that a computer executing a program cannot have a mind, understanding, or consciousness, regardless of how intelligently or human-like the program may make the computer behave.
Sirtaki is not a traditional Greek dance, it was created for the movie Zorba the Greek (1964).
Yes, Virginia, there is a Santa Claus.
Bath foam prevents water from cooling, it keeps the water warm longer.
How an aluminum can is produced.
How a plastic bottle is produced.
You can get disenshittified Google search by adding &udm=14 to the search url.
The backside of the Bahraini Half dinar features the Bahrain International Circuit.
May 2nd is the International Harry Potter Day.
Bosnian-gauge railways are widespread in Austria. This is a legacy of the Austria-Hungarian Empire.
If you divide 1 by 998,001 you get all three-digit numbers from 000 to 999 in order, except for 998.
King of the Netherlands has a commercial pilot license and (co-)pilots KLM flights regularly.
A small Austrian village Serfaus has a 1.3 km long underground.
All maps in China must use GCJ-02 datum which obfuscates coordinates by applying random shifts.
Apple produced video game console and digital cameras in 1990s.
Palau’s capital Ngerulmud has no residents.
The Cinta Coster (Coastal Beltway) is a bypass of historical part of the Panama City built right in the ocean.
French word vasistas originates from German was ist das? Which is literally What is that? and means fortochka – a small ventilation window, which in turn is borrowed from Russian, which in yet another plot twist originates from German word Pförtchen (small door).
The Romanian word for chainsaw (“drujbă”) comes from “Дру́жба” (Drúžba, meaning “friendship”), which is the name of a Russian trademark that heavily exported chainsaws to Romania during the Communist era.
Estimated 3 millions mines were laid before the battle near El Alamein in the Second World War, most which remain there. The place is now called Devil’s Garden.
GMC made a motorhome that pumped sewage through its exhaust on purpose.
15% of 5586 companies in the world older than 200 years are in Germany. Many of them are, unsurprisingly, breweries.
Popular German children detective series Die Drei ??? is based on the American The Three Investigators series, which I read when I was a teenager.
Mudflat hiking is hiking during low tides popular in northwest Germany and nearby countries.
A triple gauntlet track in Kaufungen, Germany.
Crayon color picker was added to Mac just for fun.
The IKEA effect is a cognitive bias in which consumers place a disproportionately high value on products they partially created.
IKEA meatballs were introduced 40 years ago.
Airport runaways are numbered with regard to magnetic north, except in northern Canada, where they use true north due to their proximity to magnetic pole.
Apple TV intro is made with practical effects.
It is possible to run Linux in a pixel shader. (Remember LLM in a font file from 2024?)
The Darién Gap is a remote, roadless, and dangerous area of rainforest on the international border between Colombia and Panama.
US Mint ended production of pennies on Nov, 12. The previous discontinued US coin was half-cent in 1865.
There is a single track metro station on a double track line in Bangkok BTS. Apparently, it was a temporary solution 🤷🏻‍♂️
Bulgaria joins Eurozone from 1 January 2026.
ßh invokes ssh on macOS.
How punycode works.
Typefaces designed to help dyslexics have no effect.