What Takes Time in Vibe Coding

Tue, 13 Jan 2026 00:00:00 +0000

Vibe scripting, for me, is when I develop small tools for myself with the help of coding agents. It works extremely well, especially for command-line tools.

I recently told a tax advisor about it. He was interested and wanted to see how it works. So I developed a small example on the spot: a VAT calculator. Not the best example, but I couldn’t think of anything better on short notice.

It worked well, and after five minutes the VAT calculator with a Flet/Flutter GUI was up and running.

But I could also see: there’s still room for improvement. For example, the layout wasn’t great and the functionality was too limited.

As i wanted to know how long it would take to turn it into an actually useful app, I later developed it to become a VAT calculator for all EU countries, which uses a small AI pipeline to load rates and descriptions of which product categories are subject to which VAT rate from official EU pages and displays them in an improved GUI.

The EU VAT Calculator after 2h dev time

What started with five minutes for the simple version turned into about two hours. Of course, it’s much better now. But it’s interesting how big the effort difference is between a solution that serves a specific, narrowly defined purpose and a tool with a broader scope. There’s a lot of work involved, and finesse is needed to make a tool that’s truly useful. Personally, I need iterations with a human in the loop for that. Maybe there are developers who can perfectly specify everything upfront, but I usually need to see and use something to evaluate and improve it.

AI accelerates iterations enormously, and you can decide whether to consider it “good enough” sooner or do a few more iterations. I think this is an important reason why I don’t develop faster with AI. I invest the time in more iterations and perhaps less thinking upfront, which then requires more iterations again.

Vibe Coding on Mitja Martini

What Takes Time in Vibe Coding