Technically. But as a European I'd already be in a lot of trouble for breaking the law, since the website promises to not collect personal data.

What you can do is check the javascript code for any 'http'. So open https://www.hownormalami.eu/main.js and then do CTRL-F and type in 'http'. See if any of the things you find seem to call home. Also scan over the code visually to check for any obfuscated code patterns which could hide additional instances of data transmission. In this case you won't find any shenanigans.

In general I applaud your critical stance.

I was more referring to the fact that it's possible to use it completely offline after the initial load, allowing you to use the app without risking any data leaving your machine.

That being said, I did talk to the author a little bit, and am inclined to trust him.